New member - common problem

[johnhol78]

Good afternoon everyone...

New to the group but not the joys of motorcycle ownership/upkeep

So I bought a 2005 250r from FB marketplace and knew it needed work hence it being so cheap...

IT did run a few months ago but owner had "messed with it" so wasn't when i got it.

Cranks, theres a spark, I've removed the tank and cleaned/sealed it as it was rusted out. Remove carbs and cleaned them , new float needles, new gaskets, checked all the jets....

Carbs were leaking badly out the overflow - so adjusted float heights....

Problem I have is it won't start....cranks fine....lights dim badly when cranking.

Sometimes is sounds like its going to fire but won't.

Checking compression once battery is charged again...but any obvious things to look for....not new to the game, but this has be baffled...

Has fuel, has spark (not great but blue) and assuming compression.

Any pointers?

Thanks

[Triple Jim]

Welcome to the board, John!

A compression test will tell you if the valves are all closing properly. When these engines have been run a lot without a valve adjustment, the valve lash will go to zero and it'll be hard to start and run poorly while warming up.

Cleaning these carbs is not trivial. Here is a page that might be helpful:
https://n4mwd.blogspot.com/2013/10/s...-passages.html

Have you verified petcock flow? It's vacuum operated, so if you suck on the vacuum port, it should easily open and flow well.

[johnhol78]

Actually using a temp gas bottle so gravity fed.

Was thinking I need to check the timing and valves…could be the culprit

Done numerous carb cleans and rebuilds so think I’m ok there…..

Had a thought it could be a center stand cut off but googled that and doesn’t exist lol.

Checked the left cylinder and compression was 120ish so hopefully other is the same. Based on the gate of the bike I don’t think it was maintained very well so valve clearance and timing could off

[johnhol78]

Got the bike running!!!

Adjusted the valves and now runs pretty even with the air box missing….

Freshly cleaned and sealed tank going on tomorrow.

Now I just have to work out the creaking noise from the rear end…

[CaliGrrl]

Yay for the bike back to running! And welcome, John!

[johnhol78]

Ok so with the gas IV bag lol the bike ran and idled great

With the gas tank…not so much…

Very hard to start and dies quickly…

Saw something about the vacuum? Any help would greatly appreciated

Nothing connected to the tank besides the fuel line…

[Triple Jim]

Check the flow through the petcock during cranking.

[johnhol78]

Fixed it. The vacuum hose off the carb had a bolt in the end to cap it off….

Took that out and hooked up to vacuum on the tank…

And she fired up….runs really well.

Next up brakes, and checking suspension….

Can’t get the throttle to snap back though. Lubed the cables but think it’s the control unit on the handle bars ��