RM250 90 RM 250 Starting issue

bobkyle2

bobkyle2

Its definantly going to need a piston..

The cylinder has a nikasil coating that wears away. You need to make sure that coating is still good also. IF you can get some good pictures of the cylinder walls, We can help you decide that. Usually you can look at the cylinder and see patches of the coating gone.
 
bobkyle2

bobkyle2

O ok... yeah... I would replace that piston.. It looks awful.

But truthfully if you have 200psi that is not your starting problem.
 
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drew76924

Ya the way i did it was hook the tester up and kick it about 7 -8 times until it wouldnt go sny higher and it read 200psi...im goin to try and do what u said with the carb.
 
2smoke

2smoke

drew76924:
Its sleeved no coating...just had it rebored when i did the top end last
Click to expand...

Thats your other problem. Its been Sleeved and not replated. Not that there is anything wrong with sleeved cylinders. Lots of bikes came that way. But yours didnt. Id investigate getting it REPLATED, or find a replacement cylinder that is plated. Thats one of the reasons bike manufactures went with plating. It lasts longer and is way more durable than the steel sleeve.
 
SRAD97750

SRAD97750

Moderator
Staff member
Not that anyone is wrong, but IMHO
Steel is able to be worked for cheap. $30 bore and hone jobs. Back on the road... You can get 3-5 bore jobs before replacement.
Nikasil is $275 each time. Sure it "tranfers heat better" and "lasts longer." BUT, one little nick and it's wasted. Is it 5 times better? NO.

:focus:
I think we are missing some underlying issue here.

1. Won't start
2. Carb is clean
3. Piston looks like a rat chewed on it (detonation/lean mix)
4. Oil in stator housing
5. Intake boot in useable condition (I hope, most damage is undetectable to the eye)

THESE ADD UP TO CRANK SEALS...

You MUST replace that piston and check your cylinder walls. While it's apart, crank seals, bearings, and possible trans seals.
It's worth it while it's apart. Good luck.
 
Mihylo33

Mihylo33

SRAD97750:
Not that anyone is wrong, but IMHO
Steel is able to be worked for cheap. $30 bore and hone jobs. Back on the road... You can get 3-5 bore jobs before replacement.
Nikasil is $275 each time. Sure it "tranfers heat better" and "lasts longer." BUT, one little nick and it's wasted. Is it 5 times better? NO.

:focus:
I think we are missing some underlying issue here.

1. Won't start
2. Carb is clean
3. Piston looks like a rat chewed on it (detonation/lean mix)
4. Oil in stator housing
5. Intake boot in useable condition (I hope, most damage is undetectable to the eye)

THESE ADD UP TO CRANK SEALS...

You MUST replace that piston and check your cylinder walls. While it's apart, crank seals, bearings, and possible trans seals.
It's worth it while it's apart. Good luck.
Click to expand...


Havent you said this was the problem for like the 5th time?... Good job Big Dan :thumb:
 
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drew76924

I put a new crank seal in it and tried to kick it a few times and it didnt start im goin to try and bump it again and see if it will idle normal or not and also try and get a new intake boot thing
 
2smoke

2smoke

Well reguardless of what the compression is. You NEED a top end AGAIN, from looking at your photos a new head pipe, as the one that is in the photos looks to be pretty dinged up and twisted. And probably a bore and hone.
 
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drew76924

Head pipe is fine it must be the picture its in like new condition...so my problem at this point is problably the top end as to why its not starting?
 
bobkyle2

bobkyle2

If it truely has 200 psi.. That is not your problem on why it wont start. But, I would rebuild it before continuing that thing looks like its about to come uncogged. The cylinder will need to be honed. And checked. As from here it looks awful. It looks worse than mine was and i had 150 psi.And a roached cylinder.
 
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drew76924

Il post a video on utube of me doing the compression test and of the carb apart and head off and u guys can tell me if im doing everything right
 
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drew76924

bumped it again today after replacing the crank seal (couldnt get it to start off the kick after i did the seal so i gave up and just now tried to bump it) and it started up.. rode it around on the street for 10 min or so and no uncontrolable idle and bike ran really good so we are in the right direction... its still laggy and the rpms want to hang when you snap the throttle off idle but at 1/2 throttle and up at idle and ridding it runs great no lag no hickups or anything its just the pilot jet i assume that needs to be adjusted... i shut the bike off after ridding it and it stars right up i did this 3 times and then let it sit or a couple hours and went to start it again and it still wants to start hard have to keep kicking it to get it to start....

BTW my dumba$$ forgot to tighten down the nut on the idle screw and after a few minutes i looked down and it was gone. opps... but it still ran fine no issues with it as far as ridding wouldn't really idle worth a damn but only problems i was having is that i previously stated above..

so at this point what should i do?
 
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