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What did you do to your dirty bike today?
- Thread starter byke
- Start date
2strokeYardSale
Moab on my mind
Experts, weigh in.
In my expert opinion that is a "B" piston.
Probably more important than the top is the clearance and ring gap. If they are way out your 158 hours was too late. FWIW, my pistons have way more dark carbon on top and more brown blow-by past the rings. (FWIW, all of my dirt bike pistons have come out caked dark brown; only my TZ250 roadrace pistons came out perfect mocha brown.)
You should be using a dial indicator through the plug hole to find out if there is any crank play, not just wiggling the flywheel or pulling the rod.
I have read contradictory things about piston tops. Lots of carbon indicates too lean, lots of carbon indicates too rich and putting around on the pilot jet. Bottom line is your piston went 158 hours without blowing up and I assume the jetting is right for you. If the clearance and ring gap are within spec, or just barely out, keep going 150 hours.
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thedub
Octane Socks
So you are saying I should actually measure clearances instead of going by look and feel? Hmm, your ideas are intriguing, I'll take them into consideration. 
This evening I spent like 3 hours cleaning the power valve. It was unbelievably dirty. There was so much carbon built up it wasn't even in it's original shape anymore. I have no doubt it was costing performance. I wouldn't be surprised if it had never been cleaned before (I didn't do it with the last top end) but I haven't had a fresh one apart so I don't know what the sealant looks like from the factory. What an arduous task. The parts still don't look factory fresh, but that was as good as I could do without a parts washer.
This evening I spent like 3 hours cleaning the power valve. It was unbelievably dirty. There was so much carbon built up it wasn't even in it's original shape anymore. I have no doubt it was costing performance. I wouldn't be surprised if it had never been cleaned before (I didn't do it with the last top end) but I haven't had a fresh one apart so I don't know what the sealant looks like from the factory. What an arduous task. The parts still don't look factory fresh, but that was as good as I could do without a parts washer.
PASTAPWR
Active member
Rear tire and tube and front brake bleed on CRF150. Today the kid will replace the throttle tube. Then some riding this weekend. No planned work until after Stony.
PASTAPWR
Active member
Hopefully you can find neutral! ... Don't stall!
Well, I can stall, but only when my left side is facing down hill.
2strokeYardSale
Moab on my mind
Aha! Now I can feel smug about using Motul instead of Wal-Mart oil.
Found some pics of pistons out of my 250.
thedub
Octane Socks
When you buy OE parts and every single o-ring, washer, gasket, nut, and bolt comes in it's own little plastic bag.
Kestrel
Active member
Another hundred miles in the books. Bunch of FS junk along with some spurs, many of which were pretty rutted and trashed. None of this stuff sees much use.
Sweet little nothings in the form of water crossings...
Followed by a typical steeper than it looks 20 degree or so hill climb that zigged and zagged for 50 yards to a small campsite. Ran it the first time without issue. Second time the rear kicked out and... recovering the bike was a little tricky.
Stumbled upon somebody's (presumably illegal) vacation shack on national forest land. Nice gazebo out back had a few rocking chairs. Windows were boarded up, and the front door locked. Various old bottles and animal cages surrounded the place (rabbits & ducks?), along with a hitching post to tie up a horse. Getting up there wasn't easy, either... Artistic plaque above the door read 'Southern Comfort'. Serious time investment on someone's behalf.
Followed a different spur to the top, which was super rutted and torn up. Ate it coming back down when the front tire lost traction on a clay rut. Tore a dime sized hole in my pants
Connected some more of this junk with an open section of the Blue Ridge Parkway.
Why all the dual sport junk? Well, OHV in NC is closed from around Jan 1st to the end of March... Yesterday was actually opening day, but I didn't have time to change tires back over. I've got a spare rear wheel, and need to pick up another front so that I can spoon on some more aggressive rubber. Schedule sucks for the next 2-3 weeks, but the next trip out will be up there to hit some trails.
In bad news, oil seems to be leaking out of the seal where the clutch input shaft connects to the clutch cable. When I rev the engine, I can physically see the shaft rise and lower slightly, like it's being pushed out. Smells to me like I've got some blow-by gasses making their way into the cases...
Was really trying to push off the top end on this thing until much later this summer, but I might not make it that long. 
Sweet little nothings in the form of water crossings...
Followed by a typical steeper than it looks 20 degree or so hill climb that zigged and zagged for 50 yards to a small campsite. Ran it the first time without issue. Second time the rear kicked out and... recovering the bike was a little tricky.
Stumbled upon somebody's (presumably illegal) vacation shack on national forest land. Nice gazebo out back had a few rocking chairs. Windows were boarded up, and the front door locked. Various old bottles and animal cages surrounded the place (rabbits & ducks?), along with a hitching post to tie up a horse. Getting up there wasn't easy, either... Artistic plaque above the door read 'Southern Comfort'. Serious time investment on someone's behalf.
Followed a different spur to the top, which was super rutted and torn up. Ate it coming back down when the front tire lost traction on a clay rut. Tore a dime sized hole in my pants
Connected some more of this junk with an open section of the Blue Ridge Parkway.
Why all the dual sport junk? Well, OHV in NC is closed from around Jan 1st to the end of March... Yesterday was actually opening day, but I didn't have time to change tires back over. I've got a spare rear wheel, and need to pick up another front so that I can spoon on some more aggressive rubber. Schedule sucks for the next 2-3 weeks, but the next trip out will be up there to hit some trails.
In bad news, oil seems to be leaking out of the seal where the clutch input shaft connects to the clutch cable. When I rev the engine, I can physically see the shaft rise and lower slightly, like it's being pushed out. Smells to me like I've got some blow-by gasses making their way into the cases...
Was really trying to push off the top end on this thing until much later this summer, but I might not make it that long.
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- Joined
- Apr 5, 2002
- Location
- San Jose, bottom of dirty 130
- Moto(s)
- ‘18 Alta EX006, ‘17 Alta MX019, 06R6, 05TM530 Black Dream, 01TM250 2T, ‘24 Yam Tenere 700
- Name
- Butch
- BARF perks
- AMA #: 1093637
I reached 2600 miles on the Alta yesterday. They smoothed out the washboards on Fingers and Valley View at Metcalf. Nice.
today i am going to blled the TM rear brake.
Happy Easter!
today i am going to blled the TM rear brake.
Happy Easter!
1962siia
Active member
- Joined
- Oct 13, 2013
- Location
- Rohnert Park
- Moto(s)
- 350exc-f
Aermacchi/HD Sprint 250ss
950 ADV
C&J XL350
T100SC
Guzzi hotrod
- Name
- Daniel
- BARF perks
- AMA #: 424261
Rode the KTM on the Easter ride. 100% slab but at least I was on a dirt bike. 
2strokeYardSale
Moab on my mind
Bled the brakes on the YZ250 because it likes fresh fluid. Did the rear, which I never do, and it came out as dark as good beer. The brake pedal pivot bolt was loose again, so I cleaned it, greased it, and used thread locker. If it comes loose again I'll have to put a nylock nut on the other side or something.
PASTAPWR
Active member
Had a nice day out at Metcalf on Sat. Yesterday, started getting camping stuff ready for Stony.
madsen203
Undetermined
I cleaned up all the bolts that I have removed in effort to put on new tires and new steering bearings. They had dirt, grime, and rust so I hit them with a steel brush and cleaned with a rag.
Got new (to me) tires installed. Realized I installed the front tire backwards as the leading edge was worn and I wanted it flipped but I miscalculated the rolling direction
Installed a new wheel chock opposing the existing one so I can travel with two bikes. With the upcoming winter storm...I probably won't even touch the second bike as I wanted to do an adventure ride but it's going to be a touch cold/wet to ride long distance.
Got new (to me) tires installed. Realized I installed the front tire backwards as the leading edge was worn and I wanted it flipped but I miscalculated the rolling direction
Installed a new wheel chock opposing the existing one so I can travel with two bikes. With the upcoming winter storm...I probably won't even touch the second bike as I wanted to do an adventure ride but it's going to be a touch cold/wet to ride long distance.
madsen203
Undetermined
bought a dozen pilot jets on amazon along with a measuring cup for mixing gas.
PASTAPWR
Active member
Tried to install new throttle tube on CRF150. The replacement tube does not fit in the housing. The flange on the tube is too wide. 
Put old tube back on and safety wired the grip. Purchased Camelbaks and a mini pump. Please someone, anyone, tell me; when do I stop bleeding $$$$?
That's a rhetorical question.
Put old tube back on and safety wired the grip. Purchased Camelbaks and a mini pump. Please someone, anyone, tell me; when do I stop bleeding $$$$?That's a rhetorical question.
madsen203
Undetermined
Putting on new steering head bearings today. The previous bearings were rusted out, full of dirt, and over-tightened. I will put the bike back together and load up in prep for leaving tomorrow after work!
Kestrel
Active member
Just bought a big bore kit...
... new old stock Cycle Gear Wiseco DR350 84.4mm 400cc piston & rings on ebay for $54 to the door. That's way too big for the DR350's stock cylinder & sleeve, which only had a 78mm piston. Thankfully, Suzuki copied almost the entire top end of the DR350 for their Eiger ATV line, which has a 376cc piston with a much larger and thicker sleeve from the factory.
I picked up an Eiger cylinder last year for next to nothing. Bored out for the DR "400" piston, it'll still have a sleeve thickness of around 3.7mm. Plenty.
Between a bore and hone at the local shop, plus costs for that piston, cylinder and gaskets, I think I'll have ~$165 total in the entire thing.
... new old stock Cycle Gear Wiseco DR350 84.4mm 400cc piston & rings on ebay for $54 to the door. That's way too big for the DR350's stock cylinder & sleeve, which only had a 78mm piston. Thankfully, Suzuki copied almost the entire top end of the DR350 for their Eiger ATV line, which has a 376cc piston with a much larger and thicker sleeve from the factory.
I picked up an Eiger cylinder last year for next to nothing. Bored out for the DR "400" piston, it'll still have a sleeve thickness of around 3.7mm. Plenty.
Between a bore and hone at the local shop, plus costs for that piston, cylinder and gaskets, I think I'll have ~$165 total in the entire thing.
- Joined
- Apr 5, 2002
- Location
- San Jose, bottom of dirty 130
- Moto(s)
- ‘18 Alta EX006, ‘17 Alta MX019, 06R6, 05TM530 Black Dream, 01TM250 2T, ‘24 Yam Tenere 700
- Name
- Butch
- BARF perks
- AMA #: 1093637
I took my TM 250 to Oscar (Racepace Motorsports) and he fixed my rear brake. Picked it up too. I made the obligatory mess trying to fix it myself first.
Kestrel
Active member
Oversized piston came in.
Some folks in a large DR350 thread have had issue with Wiseco's 10.5:1 replacement pistons in the DR, citing audible detonation at times. Others claim to have no issues.
I did some math on this ancient 400cc Cycle Gear Wiseco piston, and it too looks like it'll come out to around 10.5:1.
Is that too much for 93 octane in you all's eyes? Remember - this is an air cooled bike.
At worst, I could probably have a machine shop mill a pocket in the center of this thing to reduce the compression a little bit. That would preserve the squish band around the edge, and buy me a little extra wiggle room. Running race gas would be a pain (and not something I want on a dual sport). There's a programmable CDI available, but it doesn't play well without a dedicated battery. This DR350 only has an tiny and rather old/spent 12V NiMH battery up front to put a load on the system.
Thoughts?
Some folks in a large DR350 thread have had issue with Wiseco's 10.5:1 replacement pistons in the DR, citing audible detonation at times. Others claim to have no issues.
I did some math on this ancient 400cc Cycle Gear Wiseco piston, and it too looks like it'll come out to around 10.5:1.
Is that too much for 93 octane in you all's eyes? Remember - this is an air cooled bike.
At worst, I could probably have a machine shop mill a pocket in the center of this thing to reduce the compression a little bit. That would preserve the squish band around the edge, and buy me a little extra wiggle room. Running race gas would be a pain (and not something I want on a dual sport). There's a programmable CDI available, but it doesn't play well without a dedicated battery. This DR350 only has an tiny and rather old/spent 12V NiMH battery up front to put a load on the system.
Thoughts?