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Discussion Starter #1
I just rebuilt the top end on my 929. When re-assembling it, I left the charcoal canister and PAIR valve off and replaced the reed valves with block off plates, plugging the hole to the air box and the vacuum line that goes from the throttle bodies to the (now absent) charcoal canister. The bike does not run very well below 3k rpm, and it also heats up a lot faster when sitting in traffic.

Any thoughts to what could be wrong?

My plan right now is to put the reed valves and PAIR valve back in place, but that may be harder than it seems since I sort of permanantly plugged the hole
 

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do you get any FI lights? (Is this an FI bike?) Is the oxygen sensor still there?
 

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Removing the canister and putting block off plates dose not make the bike run differently. it sounds as if you have a vacuum leak. Or incorrect vacuum routing.
 

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Discussion Starter #4
figment : do you get any FI lights? (Is this an FI bike?) Is the oxygen sensor still there?
No FI lights, and yes, the O2 sensor is still in place.

Nedro, I didn't think there would be any difference in performance by leaving those items off... Do you think a vacuum leak would make the bike overheat at idle?
 

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That doesn't sound to promissing... Hope it turns out to be just a vacum leak (which I'm sure could lead to high running temperatures due to a lean air/fuel ratio) and not something more serious/mechanical.

I'm sure someone else will chime inn as well to help you.

Hope you get it fixed fast!
 

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Joel : I left the charcoal canister and PAIR valve off and replaced the reed valves with block off plates,Any thoughts to what could be wrong?

My plan right now is to put the reed valves and PAIR valve back in place,
THATS THE WAY 2 GO....
GOOD LUCK!!!!!!
 

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GAZZERUK : Quote (Joel @ Oct. 28 2003, 10:24pm)My plan right now is to put the reed valves and PAIR valve back in place,
THATS THE WAY 2 GO....
GOOD LUCK!!!!!!
Why would putting that crap back on be the way to go? Seems that everyone else on the plant is able to remove/block it without a problem. Sounds like a real lean situation and could be some vac-leak at the TB's.

Does it run smooth? Did you re-sync the TB's and if so were any of them REALLY far out of adjustment compared to others? That might lead you to the one that is having the leak (if that's the cause).

Good luck.
 

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Discussion Starter #10
booth23 : What map r u running?
No PC on it - it's all stock, including the O2 sensor equiped pipe. The only thing I did is polish the exhaust ports, and remove the stuff I discussed earlier.

The bike runs really smooth as long as it's above 3k rpm. Even at idle it's smooth, but the idle seems to vary between 1,000 rpm and 1800. When it gets low it will act like it wants to die (which it does sometimes). When you put a load on it like a gentle acceleration from a stop up a hill, it will be very rough until the tach sees 3,000 rpm, at which point it suddenly wakes up and remembers that it's a 929.

I did not sincronize the throttle bodies. The only thing I did to them is run some carb cleaner through them prior to assembling them onto the head. Do ya think that may contribute?
 

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Discussion Starter #11
I went out there and tore into it. The compression is fine - 150 give or take 10 across the board. I couldn't find any hoses that were out of place. Spark plugs look like they're about brand new, which they are. They're a very slight tan color.

Valve clearances were not so good. One of my exhaust valves is down to .002' !!! It was .012' 160 miles ago! I'll need to do a more careful inspection after the bike has sat 24 hours... it was somewhat warm when I checked them.

SUX!!!
 

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I take it you at least have cursory knowledge of how to port a cyl head?  It is possible to screw that up bad enough to get symptoms like you mention.

Also, if the porting did work, your A/F ratio is now all shot to hell which could cause idle problems.
 

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Joel : Quote (booth23 @ Oct. 28 2003, 4:04pm)What map r u running?
No PC on it - it's all stock, including the O2 sensor equiped pipe.  The only thing I did is polish the exhaust ports, and remove the stuff I discussed earlier.

The bike runs really smooth as long as it's above 3k rpm.  Even at idle it's smooth, but the idle seems to vary between 1,000 rpm and 1800.  When it gets low it will act like it wants to die (which it does sometimes).  When you put a load on it like a gentle acceleration from a stop up a hill, it will be very rough until the tach sees 3,000 rpm, at which point it suddenly wakes up and remembers that it's a 929.

I did not sincronize the throttle bodies.  The only thing I did to them is run some carb cleaner through them prior to assembling them onto the head.  Do ya think that may contribute?
Joel. Unplug your O2 sensor. Tell me what it does. I'm at work so I can't look but...Does the manual show a idle speed motor? If so, clean it out. Yes, running lean can over heat a motor but would have to be extreme.
To be honest, stumbling until 3K sounds more like rich rather than lean, but then you would be able to tell if that were happening by smell.
 

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If you feel confident about the headwork and assembly, get a PC3 or 3r and modify your fuel curve - as it would definitely be running leaner with the modifications noted. Good luck in your quest Joel.

p.s. the PAIR, airbox, and Cali emissions removal will not cause the problem you noted. You did put a little gasket sealant on the blockoff plates, prior to installation - right?
 

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Discussion Starter #15
luvtolean : I take it you at least have cursory knowledge of how to port a cyl head?  It is possible to screw that up bad enough to get symptoms like you mention.

Also, if the porting did work, your A/F ratio is now all shot to hell which could cause idle problems.
Hmmm... well here's what I did to the exhaust ports... There was a pretty huge step where the valve seat meets up with the exhaust port. I used a die grinder with emry paper on it to sand the interface down to just make it smooth, nothing more. I also used the emry paper to get rid of all the casting marks inside the port. Once that was done, I went in with Scotch brite (again with the die grinder) and made it all shiny. I took out as little metal as I could to just smooth things up. BTW, I had an experienced cylinder head guy looking over my shoulder, and he said I did a good job.

I did not touch the intake ports.

It sounds like you guys think my A/F ratio is screwed up as a result of the exhaust port work. This surprises me. Can you explain how this change to the exhaust ports has such a dramatic affect on A/F ratio?

Thanks!
 

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That doesn't sound like you could have changed flow by too much unless you significantly changed the size or shape of that step.

If you are more efficiently scavenging the cylinder, you are removing more combustion products, as well as more unburned fuel. This being the case, if the intake can keep up, you get more fresh air into the cylinder that will need fuel to keep the A/F ratio the same.

Did you make a big change? I dunno. Did you improve or worsen flow? I dunno. And neither do you unless you put the head on a flow bench and measured before and after. But there is a possibility you did improve flow and now need more fuel.
 

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Adding to that:

I'd still say you should check all the simple stuff first. To look for vacuum leaks you can take a can of WD40 and spray it around things like the TB boots while it's running. If the engine RPM increases, you have a leak.
 

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Discussion Starter #18
I'm not convinced I don't have a vacuum leak either. I fired it up last night with the air box off, and there was a pretty good sucking noise, but since I've never listened to the bike with the air box off before I have no idea if that's normal or not.

Hopefully db can come by and I'll get a second set of ears on it. Of course I've got to get the valve clearance situation cleared up first.
 

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Discussion Starter #20
nedro : Did you get a chance to unplug the O2 sensor?
Nope. I'm at work. When I get to the bike this evening I'll take care of the valve clearance issue first, then when I get that bolted back together I'll start looking at the other stuff, starting with potential vacuum leaks.

Thanks!
 
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