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Old 10-27-2011, 05:53 PM   #46
katbeanz
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Wattner, Thanks so much for starting this thread!
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Old 10-27-2011, 06:23 PM   #47
cyclewizard
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Originally Posted by willys View Post
I have another question if you can help or not I would be very gratefull for you insight.
I have a 39mm FCR-MX carb...I have it in bits at the moment and have taken it totally apart and I mean totally. I have pressed out the accelerator nozzle to clean it when cleaning the rest of it. All gaskets are still 100% intact and everything else is now perfect....BUT...in my haste to get this damned nozzle out I have damaged the slot that is meant to turn it to direct the spray. Do you know of anywhere that I can get a replacement or an aftermarket nozzle for this carb....I've been searching for hours. No my PC searching skills aren't that great as Ifound it a few days ago and now can't repeat that find.
I would be eternally grateful if you did know where....thanks again.....or to anyone else who may know.
Sudco would be your best bet for a nozzle, if the slot is damaged take some Honda bond put it on the nozzle and direct the spray and then let it stiffen up, cheap fix.......
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Old 10-27-2011, 06:30 PM   #48
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Originally Posted by willys View Post
I'm running just above 9.2, I think whatever stock is on a KLR650 2004....sorry don't know off the top of the old bean....I too am interested in the choice of decking the head or shaving the cylinder....?

Thanks for the cam timing info, already figured that part out as you have suggested. The issue is, by increasing the compression I'm moving the timing a tad aren't I? That is bringing the two systems together, crank and timing sprockets via the chain. It's moving in the wrong direction also isn't it? Which compounds my newly wanted timing ...?
This is the reason I haven't upped my compression up to now......worried about the timing issue as it isn't the easiest thing to adjust. Yes it's just a matter of boring a few new holes etc in laymans terms but it has to be extremely precise!

I'm really enjoying learning all you have to offer...it's great when a knowledgeable person shares what they know instead of hoarding that knowledge and not teaching the other up and coming mechanics so to speak.
Again thanks.
I would deck the head for more comp...decking the head will retard cam timing which will give it more over rev or top end pull.
But if you deck the head say like .020 to reduce combustion chamber "cc's" volume to up your C.R. you will have to dial your cams in.

1 or 2 cc's make a big difference in comp ratio's, to do this you will need a glass burette, it's a cc checking tool that measure's volume in the chamber.
Lets do some math here, bore size by stroke by cc volume by deck ht = what? compression and displacement.
Without knowing these items your fishing in the dark. so you need to know how deep your valve pockets are, your chamber volume, your bore size, your stroke and how far your piston sits in the hole counting the thickness of your head gasket.
you need to know these items before selecting a cam grind..and where you want to set it.
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Old 10-27-2011, 06:34 PM   #49
Ghost_Mutant
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Originally Posted by cyclewizard View Post
Because I did just that toasted cams and head journals...lots of them, I got purdy good at repairing heads and cams..
What you do is measure the amount of oil the pump puts out with a measuring cup or a glass burette per minute or break it down in 10/20/30/40/50/60 second intervals..
You mentioned in the XRL thread something about modifying the RFVC oil pump. Can you tell us the details here? Or is that also proprietary info?

I haven't toasted any RFVC engines.........yet. But my parts bike had a toasted cam/journal. I found the oil pipe for this engine in my box of parts and noticed that the previous owner had the banjo bolts swapped between the head and the case. That mistake by itself seems to have made the difference.

I feel better about my decision to upgrade my oil pump drive gears with the newer XRL/XR version on my 83/4 XRs. Older machines don't pump as much oil at idle, and Honda must have figured that out......eventually.
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Old 10-27-2011, 07:12 PM   #50
cyclewizard
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You mentioned in the XRL thread something about modifying the RFVC oil pump. Can you tell us the details here? Or is that also proprietary info?

I haven't toasted any RFVC engines.........yet. But my parts bike had a toasted cam/journal. I found the oil pipe for this engine in my box of parts and noticed that the previous owner had the banjo bolts swapped between the head and the case. That mistake by itself seems to have made the difference.

I feel better about my decision to upgrade my oil pump drive gears with the newer XRL/XR version on my 83/4 XRs. Older machines don't pump as much oil at idle, and Honda must have figured that out......eventually.
No problem, here's a few oiling mods that will help with cam and journal wear.
1...drill one size larger jet holes in your camshaft and then chamfer them with a bit three sizes larger than that, make sure you do the center cam bearing journal also.
2...you need to drill both the banjo bolts the same size...
3...enlarge and chamfer the side case oil feed holes so the oil can get upstairs to the head faster and smoother a larger line would be nice too but not necassary if synthetic10/40 is used, no 20/50 it's to thick on startup..
4...build a thicker oil pump rotor by at least .040...020 even helps alot here........this one you will need a good machinist to do this for you if your not one yourself...
5...add an oil squirter to the under side of the piston/crank assembly. another job for a smart guy..
6...steps 4 and 5 aren't that necessary for your average xr motor if you add ZDDP to your oil and use 10/40..
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Old 10-27-2011, 08:59 PM   #51
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Originally Posted by itsatdm View Post
I think what you are doing may result in problems. Back in the day when Patman Racing was going to build the ultimate KLR with either the 685 or 705, gaining compression by that route resulted in retarded timing that lost HP Lots of good info on his site, but the project fizzled at that point.

I understand degreeing the cam sprockets is a solution, I hope there is another.

I'm familiar with The Patman, we were talking when the 685 and then when the 705 kits started to be dyno'd etc. KLRCary advised me on how to best port my head even gave me pics of his ported heads to copy so to speak. I sent pics of my work to him and I got what I thought very high praise, he said it looked very close to his work and wouldn't touch it any further. I have ported many engines but usually 258 Jeep engines not bikes. Any way, I had talked to Cary about timing etc and how best to do it and he recommended 4-6 degrees for what we were doing at the time. But as we all know, he was taken from us far to early in his life, he had so much more to do and enjoy. He was the top guy for the KLR engine modifications. We are still stumbling around in the dark many years after he as left. Still can't find another person with his knowledge or love for the KLR like he had. I have done everything he suggested in regards to engine mods except degreeing my cams, as he hadn't solved that issue to exactly what was best. The person who bought the Patman's KLR got far more than I think he realizes....he has the history of the KLR engine, as Patman was Cary's test subject....a perfect match. They also had a good buddy in eagle Mike as well 3 people to round out a great team to advance the KLR, but with Cary's death, it all seemed to fall apart......I understand but what a pitty.....It was a very sad day for sure. R.I.P. Cary.

So, my next issue is this carb, then the exhaust , then I'll go after the degreeing, which is a much more complicated thing for me to do here in my garage. Once I get the degreeinf sorted out, not done just figured out, I will cc my jug and head. I do understand the process.

Again thanks and please if you can shine any more light on carb set up, or enhancements for the KLR engine as I have it already, feel free to set me straight...I'm an eager student.

Thanks...sorry for the long winded post....
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Old 10-27-2011, 10:25 PM   #52
Ghost_Mutant
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More questions!

Quote:
Originally Posted by cyclewizard View Post
2...you need to drill both the banjo bolts the same size...
Enlarge the top bolt to match the bottom bolt?, or enlarge both?

4...build a thicker oil pump rotor by at least .040...020 even helps alot here........this one you will need a good machinist to do this for you if your not one yourself...
Is that both rotors, or just the one that feeds the oil filter/head/crank? If its just the one rotor, couldn't you take a spare return/inboard thicker rotor and surface grind it down until it was .040 larger than the stock outboard rotor?

Given that the filter/head/crank rotor has the extra internal shaft seals, perhaps the bigger challenge is getting the pump housing enlarged to hold the bigger rotor. Or do you just add in a .040 shim?
Would a shim then cause interference with the drive gear? Hmmmmmm, I might have to look at my spare pump again

If its just the oil filter/head crank rotor, is there then a new worry about the return/inboard pump not being able to keep the frame tank topped off now that extra oil volume is being moved by the thicker outboard rotor?

5...add an oil squirter to the under side of the piston/crank assembly. another job for a smart guy..
Did you do this for Wattner's bike? Got photos?
Which circuit does this get plumbed into? If its the inboard return pump, then wouldn't that would further the worry about returning enough oil to the frame tank?

These things get complicated in a hurry! Perhaps you can also offer an oil pump upgrade service alongside your improved cam grinds?

6...steps 4 and 5 aren't that necessary for your average xr motor if you add ZDDP to your oil and use 10/40..
News to me, I'll look into that. Thanks!
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Old 10-28-2011, 03:01 PM   #53
Lane_N
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More info on Piston Selection

Hello all, this is my first post on the forum. Ive been lurking for a few months and am enjoying the atmosphere here on the board.

This is a fantastic thread. There is some really great knowledge being shared here. Thanks for putting this out there for everyone to enjoy.

CW:
In your post a couple of pages back where you are talking about quench and squish, you stated that a piston properly setup with .040 deck clearance will run better than the XR600 10.5:1 which ends up sitting down further in the bore (about .069 deck clearance from the information I've found available.) Does this hold true even without the more extensive cylinder head mods?

What is the upper limit for compression ratios to avoid spark knock with a stock combustion chambered head and pump gas (91 octane)? A piston set up like that with .040 deck clearance should yield about 10.6:1 static compression ratio. Is that too much, or would dishing be required on that piston to get it to run on pump gas?

How much if at all does cam grind affect an engine's sensitivity to knock?

Thanks for being willing to share your knowledge.
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Old 10-28-2011, 08:03 PM   #54
bobbed06
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Thanks for the Squish, Quench, Artificial Octane info C Dub......I understand now and appreciate the knowledge
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Old 10-29-2011, 06:15 AM   #55
cyclewizard
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Originally Posted by Lane_N View Post
Hello all, this is my first post on the forum. Ive been lurking for a few months and am enjoying the atmosphere here on the board.

This is a fantastic thread. There is some really great knowledge being shared here. Thanks for putting this out there for everyone to enjoy.

CW:
In your post a couple of pages back where you are talking about quench and squish, you stated that a piston properly setup with .040 deck clearance will run better than the XR600 10.5:1 which ends up sitting down further in the bore (about .069 deck clearance from the information I've found available.) Does this hold true even without the more extensive cylinder head mods?

What is the upper limit for compression ratios to avoid spark knock with a stock combustion chambered head and pump gas (91 octane)? A piston set up like that with .040 deck clearance should yield about 10.6:1 static compression ratio. Is that too much, or would dishing be required on that piston to get it to run on pump gas?

How much if at all does cam grind affect an engine's sensitivity to knock?

Thanks for being willing to share your knowledge.
Your motor will run fine with 10.5.1 C.R. and .035 to .040 deck ht.,,,in fact it will run way better with less chance of knock using 92/93 octane fuels and a flat top slug.
In theory a flat top piston in a wedge chamber gives the best flame characteristics, that is fastest travel speed across the chamber with excellent squish and quench characteristics. Pop up domes get in the way of the flame front slowing it down which is compensated for with excessive ignition advance which then introduces problems with detonation and preignition combined with high fuel consumption and emissions. A circular dish piston reduces compression to that tolerable by the fuels used, these are typical of OEM low manufacturing cost solutions, these have poor squish and quench as too much of the piston crown is too far from the head's squish/quench deck to be effective. This results in a tendency to detonate and preignite combined with poor power and excessive fuel consumption. The D dish piston keeps the flat top's fast burn rate, eliminating the use of excessive advance and its problems,it brings the flat top's excellent squish and quench characteristics making for much greater detonation and preignition resistance, this is often referred to as mechanical octane. Like the flat top, it pushes the mixture into a pocket in front of the spark plug giving a more reliable light off and through burn for good power and lowest fuel consumption with that power. The dish is available in several volumes and with the deck clearance space, head gasket volume, and combustion chamber space is used to optimize the compression ratio that available fuels can tolerate.
A digression to squish and quench. All engines hemi, pent, or wedge use this in some design form. It is an area where the piston and head close very closely together. With hemi's and pent's it's located around the outside diameter of the bore pushing the mixture toward the middle. On a wedge chamber it is found on the side opposite the sparkplug and valve pocket, pushing the mixture toward the sparkplug. These parts, or features of parts, perform two functions; one is squish the other is quench. They are separated by time in the cycle of compression to power. Squish happens first on compression as the flat surface of the piston closes toward the matching surface of the head. This ejects the mixture toward the sparkplug with great force both stirring the fuel and air together and increasing the density of the mixture directly in front of the spark plug. This both improves the chance of the plug lighting a burn (reduces miss and late fires), and it speeds the burn so cylinder pressure is optimized for piston position to press on the crankshaft with the greatest force possible (best power and use of the energy you pay for). At what is called the "late burn" part of the cycle is where detonation is like to occur. The temperatures and pressures ahead of the flame front are getting very high to where the remaining mixture is entering the "diesel" zone where it's happy to just blow up. To counter act this tendency is now the quench function of the close fitting parts of the combustion chamber. This is now a zone with a lot of surface area to volume, so it acts as a heat sink, delaying the point where the temperatures and pressures become so great that the mixture explodes instead of burns. These days of restricted octane fuels has made this feature very important as you can no longer just throw more Tetra-Ethyl-Lead at the problem.”
You can actualy turn the XRL's hemi head into a pent roof head but with canted valves,,with a little welding and machine work to give you a better burn and less detonation. You can even turn it into a dual wedge fast burn head.
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Old 10-29-2011, 08:18 PM   #56
Lane_N
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Thanks for the detailed response, This stuff is great reading.

Now, are you currently making a piston that sets the deck clearance where it belongs for the 100-102mm bore? If you aren't cutting that flavor, is there a readily available off the shelf alternative that would work?
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Old 10-29-2011, 08:39 PM   #57
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subscribed, good information
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Old 10-30-2011, 10:42 AM   #58
Wattner OP
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HRC Camshaft

Well, I just got off the phone with CW and I am pissed beyond words.... He tore into my motor that supposedly had the HRC cam in it and discovered a melting Hotcam. This was my motor that melted down a couple of years ago and was sent to XR's only for a rebuild.

I know for a fact that when the motor went south that I sent the HRC cam with the motor. I recall the cam appeared to be in good condition, but maybe it was scored beyond use... I simply am not sure. Before I throw stones, I will attempt to find the receipt for the motor build. More things were revealed... NO carillo rod, coated piston skirts, silicon valve springs, etc, etc.... Looks like I got ripped off. I will update once I have confirmed what was paid for with the receipt... I know it was $2,800.00 or more

With all of this being said, I will be sourcing the specs for the HRC cam and am hoping CW can still replicate the exact specs. We discussed, in great detail, what I liked and did not like with all of the cams and will come up with one that performs like the HRC to the best of our (CW's) ability.

I apologize in advance that I got hopes up for an HRC cam and now cannot deliver the specs, as it appears I have been ripped off.

Update to follow.

FWIW, CW will install one of his rods, pistons, cams, rockers and the correct valve springs and massage the oil ports, oil pump, etc, etc.... The old girl will live again!!!!! We may even keep the burned fender for kicks and the story!
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Old 10-30-2011, 11:04 AM   #59
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WOW...

thats horrible! keep us updated for sure, really that's suable in my opinion...

and I hate frivolous lawsuits but that right there is plain and simple LYING

good luck
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Old 10-30-2011, 11:14 AM   #60
Wattner OP
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Carburation

CW, can you discuss some of the idiosyncrasies of carburetors, tuning and your experiences with different carbs?

I remember back in the day of the "New" XR650L and the Honda boys sourcing the CV carbs for the big breather motors for desert work on the kickstart RFVC bikes. If I remember correctly, they took the CV carb, bored them, reworked the diaphragm and a few other internals and had them working pretty good. I used the Mikuni Flatslide at the time with great results... Now with the Dave's mods and pumper carbs, what is the hottest set-up, or once again benefits of each carburetor that you have used.

I know we have spoken about the Mikuni 42 pumper and have several of them now. The good thing about the Mikuni is there are only 3 circuits and jetting is easier than the KeiHin, especially on stock or close to stock motors.

The Keihin is more complicated and has more circuits, so it can be dialed to tighter tolerances, but you have to REALLY know all of the circuits inside and out and the symbiotic relationship of a small tweak in one circuit and it's effects on another.

Admittedly, one of my weak-spots is jetting. I have no problem with the old Flatslide, a stock CV and a Mikuni, but the KeiHin is beyond what I WANT to mess with. I like to ride and wrenching is ok, but I simply get frustrated tearing the carb out multiple times for little tweaks, so I end up with just riding when I get close and am missing some performance with the KeiHin.

I have several of the Mikunis now and want to try the KeiHin (since CW will do the tuning...) I have sold one of them (used..) to Garry (CW is beginning a build on his "L" now) and still have another new Mikuni 42 pumper carb with many jets and cables that I would like to get rid of if anyone is wanting a friendly to tune, so to speak pumper carb. PM if anyone is interested.

In the end, we will have a CV, Mikuni Flatslide, Mikuni Pumper and KeiHin to play with on the different motor configutrations.

I know each motor configuration and exhaust all play into the mix, please share some info when you have the time, and if you don't mind ;-)
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