hard to start, runs good, pops and cracks at high rpm (before redline)

[flying-pez]

Hello all, ive been through quite a lot with my xs400 and I am not going to be happy till I get it right. ive leaned a lot via trial and error and had the thing apart several times over the past few years. Ive finally got everything sound on the chassis but as its always been its hard to start. I always kick and kick it and nothing happens then it starts right up and runs great as soon as I spray starter fluid in the carbs. for some reason recently when I am on the highway it pops and cracks and I cant do.much more then 65. It also does this when I ring out the gears.

A side note, a friend of mine wanted to help me out one night and clean up my engine some. In doing so he popped out all of the black plastic bushings in between the cylinder fins and now the engine is noisy as all hell. is that the reason and if so where can I get replacement bushings?

Thanks, Pez

 

[drewpy]

so what your saying is;

1) you put your own fuel in the engine (via starter fluid) and it starts, but not sure why it won't start otherwise?

2) you have a quiet engine, take the fin dampers out and it becomes noisy and your not sure why its noisy?

 

[xschris]

Put the engine dampeners back in you need to have them they put them in for a reason

 

[flying-pez]

No, I have fuel in the bike and as long as my tank is filled it will run once started. also I no longer have the dampeners they were thrown out with the used neverdall. I was just making sure that wax the prob. And not something else. further more, the carbs are clean ive had them off prob. A dozen times over the corse of building this bike.

Forgot to post a pic of my bike.

 

[xschris]

I have a used set of them if you want them $20 shipped Has the carbs been synced?

 

[flying-pez]

I synced it a while ago but nothing changed.

 

[drewpy]

check the enricher on the carbs.

 

[flying-pez]

That may be it. Choking has never helped. What am I checking for?

 

[drewpy]

seals are intact, no air leaks there

 

[HoughMade]

The popping and loss of power at higher speed sounds like fuel starvation, either from the carbs not getting enough fuel, or from blocked carb passages. It could be an air leak as well. A messed up petcock could cause low fuel flow and an intake leak (or either), check that.

A messed up petcock could cause hard starting as well.

Have you tried starting the bike on prime? Have you confirmed good fuel flow on prime?

However, when you say the choke (enrichener) doesn't do anything, that leads me back to clogged passages in the carb. Yes, I know you said you cleaned them. #1, they don't stay clean forever (did you add an in-line filter?), #2 there "clean", and then there's "clean".