By Scott Davis on Unrecorded Date: Edit

i am haveing problems with my jlo. just recently i was looking for a piston to replace the L295 but didnt have any luck so i had to go with the L297 piston so i had to bore out the sleev and all went well. so i stuck the engine back together and put it in and started it up and it did fine BUT... i caint get it to run straight
i am pretty sure its the carb but caint tell for sure i was wondering if anyone can help me with this or any suggestions thanks

scott

By kush on Unrecorded Date: Edit

Scott,
as they say an engine is just a big air punmp. You've made the pump gulp more air. Figure out percentage wise how much more volume that bigger piston is. That should give you a rough estimate of how much bigger a jet the carb should need. a 295 is 17.8 CI & a 297 is 18.1 CI. My snowmobile manual state sthey use the same carb. I don't have the carb section to check for jet size though. On Tillotson HR carbs which it may have (Initial adjustment is both needles open 1 turn)

Good luck

Kush

By Scott Davis on Unrecorded Date: Edit

hey thanks kush i am going to try that hey what do you think the best spark plug would be to use?

By kush on Unrecorded Date: Edit

Scott,

JLO service data from a snowmobile manual states

L295 L297
Bosch M240T1 M225T1
Champion K57R UK10
Gap 0.018" 0.018"
0.4-0.5 mm 0.4-0.5 mm

Attex Manual L295 Champion K8G 0.016-0.020"

Good luck
Kush

By Scott Davis on Unrecorded Date: Edit

ok a few more things i tried the needles out one turn more than factory standards still nothing it kinda acts like it is too rich cause the spark plug is oily Do you think trying the spark plug for the l297 would make a diffrence? if not can you think of anything else? hey thanks for the help
scott

By Eugene Kochnieff on Unrecorded Date: Edit

Has the boring changed the port timing, sometimes with high performance 2 strokes they cannot be bored for this reason. Also check the piston with the old one sometimes the port timing is modified by changing the piston skirt length/ shape.
Any good small emgine shop or karting tuner will be able to give you answers on these issues.

By scott davis on Unrecorded Date: Edit

from what i can remember the skirt was the same length

By SCOTT DAVIS on Unrecorded Date: Edit

still NOTHING

By Eugene Kochnieff. on Unrecorded Date: Edit

Hi Scott, another idea, how do the mufflers of the 295 and 297 compare? A small difference in exhaust tuning can really kill a two stroke. It is also worth checking if the muffler is choked with oily deposits, these are easy to clean put the muffler in a small fire and burn it until no more smoke comes out. Obviously take it off the engine and dont do it if it is a chrome muffler as this method ruins the plating.

good Luck.

By Attex Bob on Unrecorded Date: Edit

Scott: Can you give us a better description of the problem? Does it miss at high speed? Does it run rough at idle? Is it low on power? If it runs rough all the time and is low on power my best guess is you have an air leak in the case somewhere. Easy to do but hard to find. Could be a barrel to case or case to case. If you have the tools you can pressurize the engine and look for an air leak. The reed valves should seal up the carb side and the piston should seal up the exhaust side. I have an idea that air leaks on two strokes caused more sane people to be committed than any other problem. Best of luck with your problem Scott.

By George on Unrecorded Date: Edit

Since we're on the subject, if you determine there is a leak, how do you fix it? My 252 is suffering from the symptons that Bob described on the last post. I also see evidence of a leak, since the engine appears to be running rich, there is a slight fuel leak coming from the head. Is the answer just to change the head gasket?

Any help will be appreciated.

George

By Attex Bob on Unrecorded Date: Edit

George: If you have a barrel to case leak; then the best thing to do is take it apart, clean, clean, clean, and then assemble with a new gasket. If it is a case to case leak then the best thing to do is tear it down and clean it really good and then put some loc-tight anaerobic sealer on it then put it back together. I really like that anaerobic sealer that they make. I put my T20 back together with it and it sealed it up like I welded it together!!!! It is a true high tech sealer. P.S. Before you put it back together check everything for straightness.