DR650 790 Big Bore Installation and Review

[doug s.]

Originally Posted by TinkerinWstuff

You're probably right.

But checking ring gap is as day one basic as checking plug gap. So the guy who directed the "lame" comment toward Jeff is way out of line.

while i agree w/your second comment - i also don't think jeff is lame - i must respectfully disagree w/your first comment. i suspect many folks are clueless about needing to gap rings, especially when they buy a complete piston/cylinder/ring kit. i'd wager less than 1% of people who are familiar gapping spark plugs have no experience whatsoever when it comes to installing new pistons/rings in a cylinder.

doug s.

[Jeathrow Bowdean]

I really like this thread that planemanx15 started, and I'm sorry that things went a little bit south with the show, but I know that those who follow this will learn much of what goes on in the mechanical field.
Those of us that tool know all to well that a simple project sometimes needs hands on at curtain times, and to not know this can catch you off guard !!!

We never stop learning from simple mistakes, and this is human nature.

I'm glad that Procycle is helping to fix this small stepping stone, so it's hats off to him and many of the others that offer support for this build.

I can't wait for part 2 of this to continue so we can all hear about the story of the 650 to 790cc transform project.

I hope that planemanx15 gets the info that he needs to dial this bad boy in, and if he needs any help in tuning, that my friend who lives down in the USA would be more then willing to see this get off the ground.

I'm running my DRZ stock to the end of this year, but it to will see the BB kit when the snow flys in the 2013/14 year once it is broke in at 15 000 kms. The 400 to 434cc transform is the build I'm after unless I buy another DR 650.

From Jeathrow Bowdean in Western Canada

[TinkerinWstuff]

Originally Posted by doug s.

i'd wager less than 1% of people who are familiar gapping spark plugs have no experience whatsoever when it comes to installing new pistons/rings in a cylinder.

doug s.

Probably true and I wasn't trying to say otherwise.

But it really doesn't matter and no need to derail this any further.

[xlcc]

Planemanx15;I've been following your build as at some point I'll do the same.I just can't seem to leave things the way they come.There are others on this site just like you and I.Don't feel bad maybe a little bummed out though.No body is perfect,we all learn from what we try.I am by no means a mechanic but when I bought my first bike in a box I had to get my old man to haul it home in a utility trailer.Now this is when I started to learn about bikes and how to hot rod them as I could'nt afford a real mechanic, I chock the mistakes I made as the cost of edjucation that I would have to pay a mechanic anyways.That was over 40 years ago and I am still learning new ways or trying to build something the way I want it to be.I give you a big pat on the back for trying.My old man thought I was crazy for wanting to ride a motorcycle but only a dog in the back of a pickup knows why a biker likes his face in the wind!

[Jeathrow Bowdean]

What I've learned in this build when it comes time to do my DRZ 400 !!!

- 94mm jug and pistion, with +4mm rod - New cam chain - Cams - Hardend shifter rod - Clutch - FMC 39 flat carb - My new MDR tuned pipe and SSM muffler will work for my kit - Plane head - Water pump seal - Coil - High rpm rev box - EGT pyrometer - Rpm gauge....

There might be a few other thing to consider in my build, but this 790cc transformer that planemanx15 is doing, is the cream of the crop when it comes to the word thumper pumper.

I'm using my buddy Eddie in the USA to help me with mine, so there is no second guessing for this stuff. I know enough to get me by, but when it comes to super tuning, only the best will do.

Rock on planemanx15. I can't wait to see the wheels turning when the snow is gone.

From Jeathrow Bowdean in Western Canada.... I remain.....

[Xcuvator]

Originally Posted by davesupreme

sorry dude, but i bet you're a democrat....

it's all gotta be somebody else's fault....

You would loose that bet davesupreme.

My point of view is that if the parts were sold as a complete kit, mention of the ring gap (at least) should have been made if they weren't already gaped to the bore. Is the buyer also supposed to check the piston clearance to see if the bore needs finish honing?
The offer of a discount piston is a good gesture, but to say the rings weren't gaped was because the exact ring gap is a personal choice, is what was hard for me to understand. Piston clearance and ring gap isn't rocket science.

[davesupreme]

i'm makin' a joke, boss.....

and in regard to this whole dealio.... there's no shortcuts to any of this stuff.....there's millions of aftermarket parts on the internet that will turn 'yer old scoot into the next motoGP winner, and everybody reads the stuff and then gets out their credit cards.... and all the bike forums have stories like this, where the best intentions went south, and then everybody starts to blame each other.... proper prior planning prevents pizz poor performance!....every one of these manufacturers have all the specs someplace in their info, and it's nobody's fault but your own if you don't study enough... that's my main point!... people today don't wanna take any responsibility for their own actions, and then after they make a mistake because of the previous P rule, it's somebody else's fault!.... call visa, put in a claim, get yer' $$$ back.... visa don't care, half the time they give it back, the float they make is fukkin' gargantuan to say the least....

sorry, i'm old school, that don't fly.... this motorbuilding stuff ain't easy, it ain't simple, and most of the fun to me is figuring it all out and doing it right! and you gotta get a set of mics, and learn how to measure....i get off on knowing what i'm doing, and i really hate doing things half azz.... and if you ain't got that attitude, you oughta stay away from the tool box, or don't whine when it goes south..... it will be a painful learning curve..... as demonstrated here....

the knee bone is connected to the elbow bone.... you gonna blame the supplier if he timed the cam wrong and the valves hit?... how about if the head's torqued wrong? cam chain adjuster not right?.... valves adjusted wrong cause' the cam's in the wrong place?....piston circlip comes loose cause' it's in wrong?....this stuff in the directions too?..... i think some of the posters here must be injury lawyers....

ain't no way i would put something like this together w/out miking every last part, checking the bore, piston size, etc.... there's a guy on the KTM forum fighting w/some of the big dogs over a cylinder/piston that went south on a snowbike because of incorrect thermal expansion in the cold snow w/an iron liner/forged piston combo that was too tight and the liner didn't expand enough in the cold.... and these were extremely experienced engine builders that bunged up some dimensions.....and just cause' they were experienced didn't preclude the fact that the dimensions were wrong and it fukked up.... the motor doesn't give a shizzit what you think!... kinda like the honeybadger..... you gotta do your homework, and measure twice, cut once grasshopper....

the OP never even mentions the lower end?... what's the rod/crank doing?.... if yer' gonna go this far in, you probably better do the whole 'full monte'....

and yo, planemann.... it ain't no thang... i ain't trying to bust yer' chops at all... so it didn't work... fix it and make it right, and it's all good!.... ain't no problemo.... if i had a dime for everything i've done that went south, i'd buy a nice new bike.... you ain't been hardly talking at all, it's all these other whinin' fukks that gotta chime in and start hatin' and blamin' when they ain't even gotta dog in the fight....

[refokus]

Originally Posted by davesupreme

i'm makin' a joke, boss.....
but your own if you don't study enough... that's my main point!... people today it's all these other whinin' fukks that gotta chime in and start hatin' and blamin' when they ain't even gotta dog in the fight....

[desmodab]

Here's a thought - the OP clearly didn't know to gap the rings. Woops.

Judging by the last 4 pages of posts there are a lot of he-men and die hard experts on here who wouldn't DREAM of touching an engine without gapping them and as they have so clearly illustrated it is one of the most, if not THE most basic thing anyone installing a piston should know. So basic in fact that they say it should not even be included or mentioned by the vendor in the instructions for their kits.

Interesting that not one of these guys happened to mention it or suggest it to to the OP in the first several pages of his posts as he was doing the installation.

One of the main reasons to come to ADV is to share information, sometimes to help others out, sometimes to learn. He was clearly sharing his project with us, if it is so basic why didn't any of us post him and say "don't forget to gap those rings...!!"

I just feel bad for the guy and hope he gets it back together soon.

[procycle]

Originally Posted by desmodab

Mistakes happen, even by veterans and professionals.

Oh, yeah. I have had more than my share of learning experiences like this. I have no doubt that there are still some waiting for me in the future.

[Rob.G]

I'll admit I didn't know about having to gap rings. When I did my snowmobile top end years ago, I didn't gap those rings. But, the rings came with the piston, so odds are very good they were already set.

I'm sure there must be something in the instructions with the 790 kit about gapping the rings, especially since Jeff has posted here and in the DR650 Thread about the gap and stuff.

I was going to ask there, but it seems more appropriate here -- for somebody who DOES know what they're doing with regard to gapping rings, can you explain step-by-step how to go about it? I'd sure appreciate it, since I'm gonna be doing a 351 big bore on my KLX soon, and then the 790 on my DR end of the year.

Rob

[davesupreme]

Originally Posted by davesupreme

i don't know it off the top of my head, but there's a ratio to the ring gap/bore size that's pretty much universal ..... .xxx ring gap clearance times bore size in inches... here's the weisco one....

http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

never hurts to measure twice, cut once.... grasshopper...(i love that shizzit!....)

one of my favorite sayings is... "we learn life thru suffering...."....

check out the wiseco page.... google it, there's alotta directions... rings have to be gapped since the invention of internal combustion engines.... all the piston manufacturers will have specs listed....

everybody's gettin' hissy... i ain't really trying to at all... it's just about heat and expansion..... you gotta set them, no way around it....

and when somebody early on axxed the OP about setting the gap, and he sed he didn't, that was a bad sign.....

[alpster87]

Sorry to here about OP`S misfortunes as well ,however in his first posting he states how he has read the service manuel from cover to cover ...and in the manuel it says to check ring end gap before installling piston in a step by step instruction for cyl and piston install... Note; Before installing piston rings measure the free end gap of each ring using vernier calipers Therefore putting no blame on anyone in the Forum for his own misfortunes..

[bkoz]

Thanks again to the OP for posting the build and the issues he is having. And for keeping a good attitude about it!

[bkoz]

Originally Posted by alpster87

Sorry to here about OP`S misfortunes as well ,however in his first posting he states how he has read the service manuel from cover to cover ...and in the manuel it says to check ring end gap before installling piston in a step by step instruction for cyl and piston install... Note; Before installing piston rings measure the free end gap of each ring using vernier calipers Therefore putting no blame on anyone in the Forum for his own misfortunes..

Can you explain using calipers to measure the end gap a little better?

I have always measured end gap by putting the ring in the bore then chasing it with the piston (to keep the ring straight in the bore). I then take the piston back out and use feeler gauges to check the gap. Not a bad idea to check top, bottom and middle of the bore either.