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9/7/2011
Location
Block Island, RI
US
team466
8/18/2014 9:35pm
8/18/2014 9:35pm
Edited Date/Time
8/21/2014 7:28pm
I just had eric gorr do a 144 conversion on my sons 2005 cr 125. I sent them the entire top end when i shipped it, piston ring and last used plug included. They told me the jetting looked pretty good, although i may want to go one size up on the main, I asked for more mid to top.I went up one size on the main as suggested during the install. We rode a practice day on saturday to make sure things were good. plug one was taken out after a 15 minute ride. The color look good so I put in a new plug and he rode 2 more 15 minute sessions. He said the bike felt real strong and was not pinging. Changed the air filter and put it up for the night. During morning practice the top seized. Plug 2 is the plug taken out after the seizure, all white on the insulator and no color. A friend had a 125 cylinder and top end so we installed it using the modified head. Son rode 4 motos on that set up. Plug 3 was taken out after those 4 motos, some color but not as much as I would have thought, I did not change the jetting. Any ideas about what may have caused this failure?
What fuel, oil and ratio?
Paw Paw
The Shop
http://www.goforwardmotion.com/pdf/2%20stroke%20top%20end%20and%20perfo…
Did you use the same fuel when you switched to cylinder #2? Was it low on coolant when you swapped top ends? Odd it ran fine on cylinder #2 with no changes.
Ctb, I will check that link , used same fuel, no loss of coolant, I thought it odd too that 2 nd cylinder ran ok .
We run a full bills pipe and silencer , Eric said there should be no problem with it. Thanks for the replies guys , keep the info coming, my kid was ripping on it when it was going, need to get it figured out.
Also, Why aren't the exhaust bridge holes drilled?
Paw Paw
third photo is of failure/exhaust side. there are two oil holes drilled near the top of piston.
Pit Row
It's rare, but maybe the coating is flaking off the cylinder. That, or it ingested some dirt. The slightly shiny color of the piston makes me think the coating is coming off, but usually it's nowhere near that much grinding on the piston.
The streaks on the cylinder- are they carved into the wall of the cylinder, or are they bits of aluminum deposits on the cylinder wall? Take a SOS pad and see if the streaks can be scoured off. If they can, I'd lean toward it being a dirt problem.
The cylinder coating is amazingly tough. Several years ago we were at Pismo dunes, with my son on a paddle tire equipped RM65. He would leave it in third gear, wfo, for minutes at a time. At some point the water pump seal failed and he ended up running it sans coolant. It seized going up a big dune, tight as a drum. Got it home and pounded the piston out, used muriatic acid and an sos pad to clean the cylinder up. No damage to the cylinder, even the crosshatching was still good! Bike ran like a top for 2 more years with just normal piston changes.
Check reeds (weird flow from somewhere) and most definitely check squish.
How well sealed is your air box?
Pawpaw would you drill holes in the piston for a pw50 rebuild? If so wear would you drill them for the pw? Thanks
One of the reason's I like the Suzuki 125 it has a triple ex port and no bridge. As far as a PW I don't think they have a bridge in the port. The bridge keeps the piston rings from bulging out too far and then hanging on the edge of the port.
He had Wiseco making his pistons then (for the people making negative comments about Wiseco pistons we ran their 101.5's and their 144's with NO PROBLEMS EVER).
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