I installed a BB331 with the help of a buddy a few days ago. I'm having a problem and hoping to see what you guys think before I tear back into the engine.

This is for an EFI bike.

After the install it fired up but took some time before I could get it to idle correctly. I played around with the fuel controller until it idled OK. Then took it for a spin.

It was quite a bit jumpy and hesitant from the get go. But I'm pretty sure it's because it wasn't getting enough fuel. (I'm using the EJK) The second time I took it out I changed the settings for more fuel and it ran normally for the most part.

So back to the first outing...

At some point I noticed a knocking/clicking sound. I first thought maybe that's just how the big bores sound. But as the engine heated up, the knocking seemed to get louder. Once the engine got to normal operating temps, that's when it happened.

Once I hit 5000 RPM the engine made a strange sound and I had a loss of power. (not electrical power, but engine power) When I backed off the throttle, the power came back. The knocking noise was back too. The problem was repeatable. Always around 5000 RPM. Needless to say, I limped her home.

Before it happened, I was hitting well over 5000 rpm with no problems. It only happened when the engine got warm.

The second day I took her out was much like the first. The slight knocking getting louder, followed by "the noise" (will explain it further down) at 5000rpm.

But then on the third day, "the noise" started straight away - completely cold engine. 5000rpm

The sound....

[EDIT] I attached a couple recordings of the sound a few posts down[EDIT]

At first I thought I didn't tighten the head pipe bolts tight enough. I could swear it sounded like it was coming from there. After some researching, I thought "detonation" for sure. But detonation wouldn't happen at 5000 rpm on the nose every time, right?

And the sound doesn't just suddenly happen at 5000rpm. I listened carefully and it kind of very, very lightly starts around 4500rpm and kicks in big time at 5000.

So today I pulled the plug and here's what I got:



I would say it looks "dry fouled" or "carbon fouled". I had the original plug the bike came with and used it as a test. Took the bike out for a few minutes and here's what I got: (before pic on left, after on right)




In only a few minutes that plug became a lot darker.

Now I'm not really sure what the problem is. I'd tear back into the engine, but I'm not sure what to look for. My buddy did most of the work; he won't be able to help me for another couple weeks at best. It's my first time digging into an engine like this, but after helping him out, I'm confident I can open her back up and fix whatever is wrong.

There are two things at this point I'm not sure about:

1. When my buddy tried to put the cir clips into the piston, they were quite difficult. He decided to use the original clips from the 250 piston. He said they should be fine. Would that be a possible problem?

2. My buddy mentioned he thought the two piston rings were opposite. He said they're usually silver ring on top, darker ring next. (just like the stock piston has them) But this piston had the darker ring on top. I had thought they came from Bill Blue already installed (I bought this kit new, not directly from Bill). I figured if he installed them, they must be correct. But now I'm not sure if he actually does install them. Waiting for Bill's email reply on this.

Maybe loss of compression? I don't see any leaks anywhere. Though there was a TINY bit of oil on the head cover gasket. It might have been left over from the install. I didn't wash the bike or wipe the engine afterwards.

Thanks for any thoughts...just hope I didn't screw the pooch on this!

 

Sounds like the ignition timing is out BUT EFI models I don't know much about.
Your buddy should have used the new circlips in my opinion. Not saying this is the problem but it is good practice (yes I did the 331 install and yes I used the new circlips)
Good luck.

 

Agree with Mav,, my guess is the timing.

Re-using clips gives you a possibility of them breaking or popping off, but I wouldnt think it is common unless they were really stretched when un-installed / installed

Good luck with it. keep us posted.

 

Thanks guys. Your input is much appreciated.

So if the timing is off, wouldn't it show symptoms from the get go? Not doubting, just double checking.

When I first took it out it was hitting well above 5000rpm at times with no weird noise or power loss. Before I got the fuel settings correct I would give her throttle and it would kick in hard after a second or two. Might have hit 7 or 8k, with a helluva boost forward!

Another thoughts...if the automatic CCT was installed incorrectly (not sure if it can be) could that cause the cam chain to jump a tooth or something? I've reset it and prob is still there.

My buddy did that part all his own. I had to watch him through the whole assembly process. He's a really helpful and nice guy. But he's local and has a local mentality about finer details. "Good enough" would be the best way for me to translate that mentality. If I didn't insist on torquing everything myself, he wouldn't have touched the torque wrench at all. "This one REALLY tight" or "this one not so tight" is the local guideline apparently.

 

Btw, would you think I would need new gaskets if I tear it down again? Assuming I take the head cover off and timing chain is fine and I get into the cyclinder to see if there's a problem. (Install the proper cir clips!)

 

A couple recordings are attached. Explaining a sounds isn't always easy; and comprehending the explanation doesn't always work either.

Took the bike for a quick ride down the block. In the longer recording you can hear a "tick" in the beginning. Not sure what that is. Came from the engine. Engine died at the end.

The shorter recording shows the sound really well.

 

Cam chain?
Do you have the stock cam chain tensioner? Oh you do. I just re-read everything.
If not reset properly, it might have skipped a tooth and screwed up your timing.
But that's all a guess from a fair shade tree mechanic.

 

Think it's time to dig back into the bike. We've got a lunar new year holiday coming up. No better time than that!

 

Not sure if the way he put it in made a difference. In the cyclepedia service manual they say to bolt on the housing first. Then insert the spring part. My buddy inserted the spring first, then bolted the whole thing on. It prob wasn't that, but who knows.

 

Can't be the ignition timing as that is all controlled by the ecu.

Maybe the cam chain timing is off

Did you ask EJK to re-program controller before fitting it. A standard EJK will not give enough fuel just by fiddling with the buttons for a big bore. Really sounds like you running super lean with a incorrect fuel curve.