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Old 08-17-2013, 06:10 AM   #17371
The Jester
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Joined: Aug 2005
Location: Cornwall, UK
Oddometer: 758
Great fun... until it went bang!

This weekend I was signed up to compete in a 3 day rally to commemorate the 100 year anniversary of the first International Six Days Enduro in Carlisle, northern England. The first day was 130 miles, followed by 240 and 100 mile days. It felt pretty cool to be lining up on my DR surrounded by a vast range of bikes, from a full factory speed brain rally bike to historic twin shock race machines. Of course the favoured colour was orange, with many of the bikes in full rally prep. There were a number of larger bikes too including several 950 / 990 adventures and an HP2

The times were very tight on the timecard but I was managing to keep ahead of the bikes behind and passing a few of the bikes ahead. I almost managed to complete the first day despite the gearbox developing a fault which resulted in it randomly changing down a gear when I came off the throttle and having to siphon some petrol from another competitor. Unfortunately on the road section on way back to the finish the bike rapidly lost all compression and ground to a halt. Without removing the head to confirm I'm not positive but the evidence is pointing towards a holed piston so it's game over for me.

Fun while it lasted but an expensive weekend.

I expect I will be asking for engine advice in a few days once I get the head removed.
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Old 08-17-2013, 06:53 AM   #17372
thump!
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Location: Northeast Tennessee
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Quote:
Originally Posted by The Jester View Post
...Without removing the head to confirm I'm not positive but the evidence is pointing towards a holed piston so it's game over for me...
Certainly possible but I've never heard of that happening to a DR350. If that's the case you must be running VERY lean.
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Old 08-17-2013, 07:17 AM   #17373
Ribsauce
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Location: Raleigh, NC
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Quote:
Originally Posted by MrPulldown View Post
Depends. If the idle is too rich you can adjust the idle mixture screw with the carb on the bike. Granted that the brass plug has already been removed. Any throttle range beyound that will require carb remove, new jets, and possibly a new needle (not the idle adjustment screw/needle).


Why do you think it is too rich? Is the air filter clean? Remove the snorkle? Has someone rejetted the bike in the past? Moved to higher elevation?
If I try to go wide open throttle it bogs down, it backfires, and the color of the exhaust is dark, all which google told me means it is running to rich.

I don't know history or rejetting or how to tell if someone did.

It is raining now but I think I know where to look for the screw. I am not sure if the brass plug is there or not, that is probably why I had trouble.

thanks
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Old 08-17-2013, 08:03 AM   #17374
thump!
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Quote:
Originally Posted by Ribsauce View Post
If I try to go wide open throttle it bogs down, it backfires, and the color of the exhaust is dark, all which google told me means it is running to rich.

I don't know history or rejetting or how to tell if someone did.

It is raining now but I think I know where to look for the screw. I am not sure if the brass plug is there or not, that is probably why I had trouble.

thanks
The idle mixture screw is not covered by a brass plug on the TM33. However it will have zero influence on wide open performance. Refer to this diagram on the Sudco website.

http://www.sudco.com/Carburetor02.html

There could be lots of reasons for poor wide open performance but changing that idle mixture screw won't fix them. What it will do if you get it too far off is make the bike difficult or impossible to start. I actually found a main jet laying loose in a float bowl once. The bike ran pretty well up to about 1/2 throttle but behaved as you described above that.
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Old 08-17-2013, 08:04 AM   #17375
Anonawesome
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Joined: Feb 2010
Location: Central OH
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Quote:
Originally Posted by The Jester View Post
This weekend I was signed up to compete in a 3 day rally to commemorate the 100 year anniversary of the first International Six Days Enduro in Carlisle, northern England. The first day was 130 miles, followed by 240 and 100 mile days. It felt pretty cool to be lining up on my DR surrounded by a vast range of bikes, from a full factory speed brain rally bike to historic twin shock race machines. Of course the favoured colour was orange, with many of the bikes in full rally prep. There were a number of larger bikes too including several 950 / 990 adventures and an HP2

The times were very tight on the timecard but I was managing to keep ahead of the bikes behind and passing a few of the bikes ahead. I almost managed to complete the first day despite the gearbox developing a fault which resulted in it randomly changing down a gear when I came off the throttle and having to siphon some petrol from another competitor. Unfortunately on the road section on way back to the finish the bike rapidly lost all compression and ground to a halt. Without removing the head to confirm I'm not positive but the evidence is pointing towards a holed piston so it's game over for me.

Fun while it lasted but an expensive weekend.

I expect I will be asking for engine advice in a few days once I get the head removed.
I'll send some good vibes and maybe the issue will change to a blown head gasket. If you're replacing the piston, get a lighter-weight wiseco piston. I don't believe they're that much more expensive than an OEM one. I will be when I finally tackle my top end rebuild.
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Old 08-17-2013, 08:20 AM   #17376
dav_dman
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Joined: Sep 2010
Location: louisville ky/southere indiana
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Quote:
Originally Posted by thump! View Post
The idle mixture screw is not covered by a brass plug on the TM33. However it will have zero influence on wide open performance. Refer to this diagram on the Sudco website.

http://www.sudco.com/Carburetor02.html

There could be lots of reasons for poor wide open performance but changing that idle mixture screw won't fix them. What it will do if you get it too far off is make the bike difficult or impossible to start. I actually found a main jet laying loose in a float bowl once. The bike ran pretty well up to about 1/2 throttle but behaved as you described above that.
agree sounds like a float/pop off/main jet issue.

pull the carbs
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Old 08-17-2013, 08:46 AM   #17377
The Jester
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Location: Cornwall, UK
Oddometer: 758
Quote:
Originally Posted by Anonawesome View Post
I'll send some good vibes and maybe the issue will change to a blown head gasket. If you're replacing the piston, get a lighter-weight wiseco piston. I don't believe they're that much more expensive than an OEM one. I will be when I finally tackle my top end rebuild.
Thanks for the vibes but I'm not hopeful. Not sure exactly which one but I'm pretty certain the bike already had a big piston - the pic of the bike as I bought it a couple of months ago gave the game away and a look down the plug hole with a torch confirmed the piston is not stock







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Old 08-17-2013, 09:10 AM   #17378
Ribsauce
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Location: Raleigh, NC
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Quote:
Originally Posted by dav_dman View Post
agree sounds like a float/pop off/main jet issue.

pull the carbs
To be clear, this is because a needle could have somehow fallen out, correct? I cleaned them last week.

At least I am really learning to work on this. A month ago I couldn't even get the carb on the bike in under 5 hours.
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Old 08-17-2013, 09:11 AM   #17379
The Jester
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Location: Cornwall, UK
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Quote:
Originally Posted by thump! View Post
Certainly possible but I've never heard of that happening to a DR350. If that's the case you must be running VERY lean.
I think I was. Plug is pale grey with a lumpy texture. Looking down the hole, what I can see of the valves also appear lumpy. The compression loss points to valves, gasket, piston or rings. The oil dripping from the engine breather when it died suggests pressure to the crankcase. I'm assuming the uneven texture to the plug and valves is fused metal. Since alloy would burn out before steel I'm assuming the fused metal is alloy from a blown piston

I bought the bike a couple of months ago as a cheap non-runner. I sorted an ignition issue and got it running but it was pre-igniting and not pulling above 3/4 throttle. I lifted the needle 2 clips to the highest setting which stopped the pre-ignition except under high load at full throttle. I was going to investigate further but then had to sort a problem with the kick start and ran out of time before the race. Unfortunately I spent most of yesterday with the throttle pinned so the bike wasn't having an easy time.
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Old 08-17-2013, 09:24 AM   #17380
2bold2getold
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Joined: Dec 2011
Location: DFW TX
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Quote:
Originally Posted by The Jester View Post
I think I was. Plug is pale grey with a lumpy texture. Looking down the hole, what I can see of the valves also appear lumpy. The compression loss points to valves, gasket, piston or rings. The oil dripping from the engine breather when it died suggests pressure to the crankcase. I'm assuming the uneven texture to the plug and valves is fused metal. Since alloy would burn out before steel I'm assuming the fused metal is alloy from a blown piston

I bought the bike a couple of months ago as a cheap non-runner. I sorted an ignition issue and got it running but it was pre-igniting and not pulling above 3/4 throttle. I lifted the needle 2 clips to the highest setting which stopped the pre-ignition except under high load at full throttle. I was going to investigate further but then had to sort a problem with the kick start and ran out of time before the race. Unfortunately I spent most of yesterday with the throttle pinned so the bike wasn't having an easy time.
Sounds like you have it figured out. Time for a new piston, rings and a hone job. Oh yeah, and a bigger main jet.
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Old 08-17-2013, 02:46 PM   #17381
kaukasion
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Having a bit of an issue guys I'm new to bikes and learning to ride on the good old doctor 350 well having an issue when I've been riding for a while the bike gets hard to shift down clutch seems to be working not real sure what the issue is. Any ideas are appreciated
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Old 08-17-2013, 04:39 PM   #17382
thump!
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Quote:
Originally Posted by kaukasion View Post
Having a bit of an issue guys I'm new to bikes and learning to ride on the good old doctor 350 well having an issue when I've been riding for a while the bike gets hard to shift down clutch seems to be working not real sure what the issue is. Any ideas are appreciated
It's a "feature" on the DR350. Try adjusting the clutch cable to have minimal slack.
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Old 08-17-2013, 09:18 PM   #17383
Anonawesome
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Location: Central OH
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Quote:
Originally Posted by kaukasion View Post
Having a bit of an issue guys I'm new to bikes and learning to ride on the good old doctor 350 well having an issue when I've been riding for a while the bike gets hard to shift down clutch seems to be working not real sure what the issue is. Any ideas are appreciated
If you ever find it to be ridiculously hard to get into neutral, rev it up a little.
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Old 08-18-2013, 12:38 AM   #17384
Anonawesome
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How do you guys recommend removing frozen screws? I'm stripping and repainting my header for no reason and the screws holding on the heat shield were as stuck as possible. My impact driver absolutely DESTROYED the rusty heads. Funny, but irritating. My only option was drilling the screw heads off. Done. Heat shield off. But now I need to get the screw body out of the hole. Is my only option to purchase a tiny easy-out tool?
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Old 08-18-2013, 02:32 AM   #17385
mwilliamshs
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well....(now that's a deep subject)

Quote:
Originally Posted by Anonawesome View Post
How do you guys recommend removing frozen screws? I'm stripping and repainting my header for no reason and the screws holding on the heat shield were as stuck as possible. My impact driver absolutely DESTROYED the rusty heads. Funny, but irritating. My only option was drilling the screw heads off. Done. Heat shield off. But now I need to get the screw body out of the hole. Is my only option to purchase a tiny easy-out tool?
Many air-cooled VW exhausts clamps, 8N Ford manifolds, Case 310 manifolds, and Ironhead Sportsters later I've learned some things about how crappy threads used on exhaust systems can be.

If there's some protruding length you could try, in order of likelihood of success (IMO of course):

1)soak the threads with JB80, then heat the threaded portion of the header as hot as you dare and spray with the threads with: freon, cold water from a squirt gun, can of compressed air upside down, more JB80, etc. Then reheat again and melt candle wax into the threads, then weld a tight fitting nut, bolt, cheap wrench, or scrap steel onto the protruding portion of the screws, then reheat the threaded portion and turn your makeshift tool left 1/4 turn, right 1/4 turn, left 1/2 turn, right 1/4 turn, left 1/2 turn, right 1/4 turn etc etc etc till it's out or breaks again. Believe it or not, everything here works and makes a noticeable difference. JB80 is GOOD stuff. The HOT then COLD trick really can "snap" a bolt loose. Like finger loose. I've done it but it works best where there's substantial mass to heat and minimal mass to cool. Candle wax is an OLD trick that works. Heat/expansion is your best friend, till you melt something you didn't want to.

2)most of the above^ omitting whatever step(s) you find superfluous

3)clamping vise-grips onto the protruding portion and attempt twisting out

4)cutting a slot in the protruding portion with a hacksaw, dremel, etc and attempt twisting out with a screwdriver

5) file the end flat, center punch it, drill with a bit 1 step smaller than the screw shaft as completely as possible but NOT into the header, then try twisting out what's left or tapping a tight fitting torx bit into its center (not so tight or so far as to expand the screw shaft!) then attempt twisting out what's left. This sometimes collapses the remaining portion and leaves behind usable threads.

6)something else entirely. make it up, look it up, or blow it up.

if there's NO protruding portion your options are much less pleasant buuuuut...

1) ignore what's left, grind it flat, or remove it entirely and weld on replacement nuts to the header then thread in replacement screws. This will look stock, save time and energy, and is always a backup plan to all others. If you opt to leave the existing threaded nubs (nuts etc) on the headers you can just scoot your heat-shield forward or aft the width of a nut and weld some on.

2) Heating the outside of the threaded nubs will help any unscrewing method but heating the screw will only make it more difficult. the heat is to expand the outer metal thus making it grip the screw less tightly. anything that EXPANDS the SCREW is BAD!

3) Cut a slot into the existing screw portion as much as possible and into the threaded nub as little as possible then using a SKINNY screwdriver and attempt twisting out the screw.

4) Keintech stainless header is like $130 and looks GOOD.

My bike, in my shop, on my time and my dime would either get Jesse's header or fresh nuts welded on and the heat-shield screwed into them. The existing stuff would get clipped off with a cutting wheel on my 4" angle grinder. Rusty threads suck. Exhaust threads suck. Rusty exhaust threads SUCK! Regardless of whether you use any of this info or not, definitely let us all know what works for you!!!

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