Make sure you re-jet once you fgure out the starting drill or the lean jetting will melt your top-end.
Visit:
Off Road.com
Visit:
Off Road.com
hard to start lt250r
G
my brother just bought a '90 lt250r. and now it will not start. what can happen that will cause this, how can i inspect for them, and what are the remedies.
as for the quad, i lknow it had good compression, maybe insane compression, it almost knocked my leg off trying to start it. it back fired a couple times. the previos owner hadn't ridden it since june and only put about 3 hours on the top end from what he claims. the fuel/oil was mixed at 16:1 for break-in. he also said it had been running at about 6000 ft altitude, and he leaned out the carb. now i'm at sea-level trying to make it run, and kicking it till i'm blue. i'll soon try to bump start it.
i'm not sure what was done to accomplish the high compression- milling the head or cylinder-or??
'-ahhh! the taste of unburnt hydrocarbons in the morning, gotta love it!'
as for the quad, i lknow it had good compression, maybe insane compression, it almost knocked my leg off trying to start it. it back fired a couple times. the previos owner hadn't ridden it since june and only put about 3 hours on the top end from what he claims. the fuel/oil was mixed at 16:1 for break-in. he also said it had been running at about 6000 ft altitude, and he leaned out the carb. now i'm at sea-level trying to make it run, and kicking it till i'm blue. i'll soon try to bump start it.
i'm not sure what was done to accomplish the high compression- milling the head or cylinder-or??
'-ahhh! the taste of unburnt hydrocarbons in the morning, gotta love it!'
1 - 7 of 7 Posts
G
i talked to the late owner yesterday. he said the only thing that has been done to get the compression so high is a 2mm overboar w/ weisco piston... no head or cylinder deck shaving (unless it was done before he had it) ..... would that make it a dome-top race piston?
the only thing he did to lean it out for the altitude was turn the air adjustment screw out 2.5 turns, other than that he claims it was tuned last at sea level.the first thing i'm going to try is putting it at 1.5 turns out.
it has a 38mm mikuni carb, the mainjet is a 330.(does this sound about right for sea level?) looks like it was ported at one point... but i don't think professionally. has a fmf gold series pipe, and answer spark arrestor on it
'-ahhh! the taste of unburnt hydrocarbons in the morning, gotta love it!'
the only thing he did to lean it out for the altitude was turn the air adjustment screw out 2.5 turns, other than that he claims it was tuned last at sea level.the first thing i'm going to try is putting it at 1.5 turns out.
it has a 38mm mikuni carb, the mainjet is a 330.(does this sound about right for sea level?) looks like it was ported at one point... but i don't think professionally. has a fmf gold series pipe, and answer spark arrestor on it
'-ahhh! the taste of unburnt hydrocarbons in the morning, gotta love it!'
G
I would reccomend draining the gas, mixing up a fresh tank full. Clean and service the air filter. Remove and replace the spark plug with a brand new plug. Then try starting it again.
If there was porting alterations there likely would be accompanying head modifications that would raise the compression. The piston in a two-stroke motor is different than a thumpers piston. Most 2 stroke motors piston is domed as standard. Typically the combustion pocket volume is altered to increase the compression ratio.
Try setting the air screw to 1.5 turns out. If it is still hard to start try cracking the throttle slightly, repeat start procedure.
Check the plug often so that it doesn't get wet from unburnt fuel. Buy a few spares.
Try those items out and post back with your results.
--Backcountry
If there was porting alterations there likely would be accompanying head modifications that would raise the compression. The piston in a two-stroke motor is different than a thumpers piston. Most 2 stroke motors piston is domed as standard. Typically the combustion pocket volume is altered to increase the compression ratio.
Try setting the air screw to 1.5 turns out. If it is still hard to start try cracking the throttle slightly, repeat start procedure.
Check the plug often so that it doesn't get wet from unburnt fuel. Buy a few spares.
Try those items out and post back with your results.
--Backcountry
G
the carb: 38mm mikuni flatslide: has 330 main,30 pilot, needle size dont recall now, but is on the third notch, air screw at 1.5
have drained the gas. will put in fresh 40:1 w/ good premix.(dumonde tech race)
i followed the advice of a wiseman and took off the flywheel cover to check if the flywheel key had sheared and if the crank seal was leaking, found metal shavings in the cover, steel .. magnetic. turned the flywheel by hand and the balancer did not turn at all. opening the oil fill plug.. i could see that the gears on the other side turn but the shaft does not. looks like a load of fun.....
'-ahhh! the taste of unburnt hydrocarbons in the morning, gotta love it!'
have drained the gas. will put in fresh 40:1 w/ good premix.(dumonde tech race)
i followed the advice of a wiseman and took off the flywheel cover to check if the flywheel key had sheared and if the crank seal was leaking, found metal shavings in the cover, steel .. magnetic. turned the flywheel by hand and the balancer did not turn at all. opening the oil fill plug.. i could see that the gears on the other side turn but the shaft does not. looks like a load of fun.....
'-ahhh! the taste of unburnt hydrocarbons in the morning, gotta love it!'
G
Check to see if the key is sheered on the counter-balancer shaft. The motor should be vibrating like crazy if the counterbalancer is not spinning. If the key is broken replace it and be sure to torque the nut to 65ft-lbs. My buddy Jason had the same problem this past summer. It turned out his crank was out of spec (0.006") and caused the counterbalancer to vibrate and sheer the key. He removed the crank (this sucks because you have to split the cases, but this way you will really know what you bought) and have it balanced. After this reinstall new seals & lower bearings and DO NOT POUND the crank into the new bearings. This can knock it out of spec. If the crank wont go in easily heat the bearings and the crank will just drop in.
Hope this helps
Langbolt
Hope this helps
Langbolt
G
the key was sheared, have replaced it, Torqued the nut to specs and wil begin assembly this weekend... i still need to check the flywheel key. but have already emptied the gas and will put in fresh 40:1 that i normally run.. dumonde tech race oil and fresh trans lube of the same make.
if it shears again i will go deeper into the engine next time.
'-ahhh! the taste of unburnt hydrocarbons in the morning, gotta love it!'
if it shears again i will go deeper into the engine next time.
'-ahhh! the taste of unburnt hydrocarbons in the morning, gotta love it!'
1 - 7 of 7 Posts
- This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Off Roading Forums
A forum community dedicated to all off road vehicle owners and enthusiasts. Come join the discussion about performance, engine swaps, modifications, classifieds, troubleshooting, maintenance, and more!
Full Forum Listing
Top Contributors this Month
View All
Form Lighting
8 Replies
Diode Dynamics
4 Replies
seoautoparts
4 Replies
Recommended Communities
