400 hard to start

[reggit]

Got a 400 that's a pain to start.  Usually have to resort to a spray of starter fluid in the airbox to get it going.  Once running it goes fine.

History 1993 bike with 1989 engine, bought as non-runner.

When going it runs fine.

What I've done:
New plugs
New o-rings fitted
choke appears to work in that it varies engine rpm from cold.
coils good

What I know; reg/rec dead - waiting for a new one, but this shouldn't affect starting only charging I would have thought.

Previous owner removed air filter and jetted carbs to suit.  Would this affect starting?  I'm waiting on delivery of a fresh filter and have correct jets to suit.

Any ideas why it won't start properly.

[tundrazach]

have you checked the compression? Im not aboslutely positive about motorcycles, but I do know that low compression in dirt bikes makes them harder to start

[reggit]

Tried that, 170-190psi across the four so well within spec.

Ta for replying though. 

[tomacGTi]

Rec/Reg has alot to do with the start, more than you think.

If your battery doesn't have the balls to turn the engine over fast enough, fire the coils, run the lights as well as run the ignition system, it's not going to fire over easily. It's the first casualty when your RR takes a dump.

When mine went out, restarts were the absolute worst. I had to push start the bike sometimes to get it going after I got gas. After awhile, even leaving the bike on the charger overnight wasn't enough and I had to spring for a new battery when it was only a year and a half old. Things got expensive quick, not to mention the uneven voltage spikes may cook your CDI as well.

You're running without the air filter? On a fresh motor? That's a dumb idea, hope you haven't run it so much as you're just doing more damage than anything.

Better get it together or else that bike isn't going to last so long.

[reggit]

Don't worry - it has only been run for a short distance to check the motor out, as it's a 2nd bike I don't need to use it.

Air filter has been on order for a good while, no stock here at the minute.

The reg/rec symptoms you describe do sound like what I'm experiencing, so I'll live in hope that's the problem.  Already bought a 'good' one of ebay that turned out to be as dead as mine.  I have another one on order.

[tomacGTi]

If the PO jetted the bike to work without the air filter, you can do what I did and get a UNI foam universal sheet and cut the shape you need. $15.

Might have to go a touch leaner jet-wise but easier to find versus the Suzuki one. GS500 RRs work as well.

[Chris H]

Hi Reggit,
The offer still stands for the free filter if you PM me.

[reggit]

Hi Reggit,
The offer still stands for the free filter if you PM me.

Chris - sent PM,
Thanks.