long ride and now what?

[Street Ryderz]

yeah that brief time that keeps getting longer and longer!again it will be after christmas before snow is able to stay on the ground to keep me from riding but im not liking the cold as much as i used to!there is a some guys here at the track running sleds in high 9s low 10s very fast very loud looks like fun!I haven been on one since the 80s old polaris 440 we thought they were quick then ha!

 

[Steve Best]

I ride a 03'Cat 660 4 stroke. Big, heavy and slow. I STILL think those 80s sleds are fast(er than me!).

 

[Street Ryderz]

Well now I am thinking the rings are worn!And I know that alot of people say that the higher cr kills these little engines but i like to play hard!anyway my compression is 132 psi and has dropped a fair bit.I was talking it over with an old racing buddy also an amazing engine builder! and he reminded me that at the start off to much wear and the change of cr now leaves it fat in the top for how finely its tuned.

Finally got around to investigating the reason for this loss of power and it was the rings but also the piston some how!I messured the piston at the crown it's 46.5mm not a big difference but still some wear around .22 of a mm but that coupled with the wear in cylinder dia witch is now 48mm and the loss of compression was enough to make for a substaintal power loss!Yet to look at the cylinder it shows normal wear whith no physical scaring!

 

[Street Ryderz]

The reason for looking at the previous engine is that my current engine is starting to do the same s**t!It starts up fine runs ok for a few min until it's warmed up then goes pig rich with no power to be had!On thursday I had to go to court 4 cities away the one way distance 80 km or 50 miles it took me an hour and fifteen min to travel the distance with a half hour stop in between for a cool down!It was fine all the way there but on the way back it just started losing power the same way as the previous engine did!The weird part is this engine still shows it's 165 p.s.i cranking pressure that it started with!I think the little end play only 1mm is the culpret here allowing the beval cut gears to pull the crank to one side and then wear one side of the jug more then allowing some blow by!That will teach me for thinking a little end play was ok! So of course now it has to be dis assembled a new jug cut and ported again and find some 15mm i.d .5mm thick washers or spacers to take up the end play!

 

[gary55]

A engine with blow by tends to push out crank seals. 165 sure don't sound like blow by. Uneven wear should show in that barely detectable ridge that shows up in a cyl. at the top and bottom, one side being more visible than the other. How bout them seals. Weak crank pressure means the charge stays in the case.

 

[Street Ryderz]

A engine with blow by tends to push out crank seals. 165 sure don't sound like blow by. Uneven wear should show in that barely detectable ridge that shows up in a cyl. at the top and bottom, one side being more visible than the other. How bout them seals. Weak crank pressure means the charge stays in the case.

That's true both seals were blown out and I replaced them before doing the comp check,and haven't run it again and wont until I get it sorted out!Kinda why I went back to look at the previous one because it's seals were intact but the same exact symptoms!

 

[Street Ryderz]

That's true both seals were blown out and I replaced them before doing the comp check,and haven't run it again and wont until I get it sorted out!Kinda why I went back to look at the previous one because it's seals were intact but the same exact symptoms!

so I took it out and the top end off and I'm kinda stumped!there is no sign of blow by on the piston and some wear to the jug but not to where I would say it's damaged, looking at the top of piston it saw some bounce you can see the ring and it shows the wash of fuel coming out of transfers across the face not very atomized and not sure why!

 

[Street Ryderz]

Not sure when I'm going to get to my engine again just got this weeks load of 2 stroke repairs 3 saws 2 quick cuts all not running!My shop is becoming the two stroke anything repair shop!

 

[gary55]

Last week I sold a new bike that was running great. Dude had it a 2 days and brought it in sating it was running bad. Everything was checking out good 135 comp. good spark getting fuel. I noticed the seal were popped out a little bit, not all they way but some. I replaced the seals. fired it up and it ran great for about 1/4 mile then started crapping out. It sounds just like what your going through. So I just started throwing parts at it. new cdi, no new mag., no new carb., no new head, no new cyl., no. I know the rotor magnet is good cause it would start and run fine for a min. or two then start bogging down and dies. Like yours super rich it seems. By now no mater how much I want to solve the prob. I'm more concerned with getting this guy his bike back so I just pull the engine and put a new one in. Now I can take my time trying to figure out what is wrong with it. the engine is brand new. Makes me want to pull my hair out. I was going to mention this earlier when I chimed in on reply # 35 but I'd had enough beers to figure it's time to think about getting off the internet.

 

[Street Ryderz]

Last week I sold a new bike that was running great. Dude had it a 2 days and brought it in sating it was running bad. Everything was checking out good 135 comp. good spark getting fuel. I noticed the seal were popped out a little bit, not all they way but some. I replaced the seals. fired it up and it ran great for about 1/4 mile then started crapping out. It sounds just like what your going through. So I just started throwing parts at it. new cdi, no new mag., no new carb., no new head, no new cyl., no. I know the rotor magnet is good cause it would start and run fine for a min. or two then start bogging down and dies. Like yours super rich it seems. By now no mater how much I want to solve the prob. I'm more concerned with getting this guy his bike back so I just pull the engine and put a new one in. Now I can take my time trying to figure out what is wrong with it. the engine is brand new. Makes me want to pull my hair out. I was going to mention this earlier when I chimed in on reply # 35 but I'd had enough beers to figure it's time to think about getting off the internet.

I hear you brother!LOL I also tried a stock cdi and checked the stator with meter! I swapped the carb for another one I had ready to go,swapped out the plug even took my exhaust off and tried a shorter header length one and all the same outcome being to rich and I went down to a 76 jet and still it was rich so I knew something was amiss!