Stumble at low rpms under load

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Here are the pics, I they look like kehin and I think I’ll need few.
Thanks

[daves79x]

Yes, those are Keihin. Do you have some that are weeping? The originals, as long as they are kept clean, last forever. You can get genuine replacements at PJ Motorsports. You'll just get the needles from them, that's usually all that's needed, but if you require the whole valve set, Honda still has them.

Dave

[cross]

Yes, those are Keihin. Do you have some that are weeping? The originals, as long as they are kept clean, last forever. You can get genuine replacements at PJ Motorsports. You'll just get the needles from them, that's usually all that's needed, but if you require the whole valve set, Honda still has them.

Dave

None are weeping i don't think but I'll verify on assembly with leak test. Few of them seem to have a line around the rubber part, can't tell if it's ridged or not and that is the reason i thought of replacing those. When you say needles you mean rubber part?
One other question i had is about the exhasut gaskets, the ones that are on the head before headers are installed. The only ones i see online are the copper ones. Are those good to use and is there a special procedure when tightening headers?

Thank you

Sasha

[daves79x]

No, I mean the entire needle you have pictured, as opposed to Honda's full set of needle and seat. You can get a set of Keihins for PJ for about $110 (price goes up pretty regularly), Full set from Honda are at least $50/each.

There are fiber exhaust gaskets out there, maybe CBX Performance sells them? But most guys just use the copper ones. The excellent OEM asbestos/wire ones from Honda have been NLA for years. Wonder why????

Dave

[cross]

I’ll have to clean mine and see if the line on them is like a ridge in which case I’ll replace them.
I cross referenced PJ part numbers and same needle valve is also for ‘10-‘12 ninja 250R and needle is available on its own from Kawasaki. It’s $30
As far as copper exhausts go, any special procedure when using them or same as stock ones? I would think that copper would need more torque so that it compresses, no?

Thank you Dave


Sasha

[Larry Zimmer]

Sasha, you don't want to go more torque than spec. Those little studs won't take it. I seat mine at 7 lbs-ft with a torque wrench. Get things square before final tightening. Th coppers compress well at 7. Gettig the pipes all square and drawing up evenly has always been my pia. (Maybe just the guy on the wrench, here!)

[EMS]

Copper crush gaskets are usually not seated by torque but by tightening angle from hand tight. That being said, it is a little complex to figure out, because the thread pitch of the studs would have to be considered.
Cometic makes a spiral wound alloy gasket for these applications. Several retialers have them. I have personally used the copper crush gaskets with torque and without problems. The issue here is to be careful NOT to pull the studs out of the head.

[cross]

I'm so glad i asked!
Cometic has a lot of them but none are listed for any Honda models. But, these seem to be the ones like performance international sells, right?
I would assume that the installation/tightening procedure would be the same as stock gaskets?

https://www.ebay.com/itm/79-82-Honda-CB ... 2104!US!-1


Thank you
Sasha

[daves79x]

Yep - those are the ones. I've used them several times, only slight issue is they are pretty thick upon first installation, such that the nuts barely start, and then there is quite a bit of crush, but not nearly like the copper. But be patient and they work fine and can be used many times. Also be sure your split collars are all fitting the aluminum collars very well. Many I've found have been caught out of the groove and need hammered into proper shape again. This is necessary for even collar tightening.

Dave

[EMS]

I would take exception to "they can be used many times"
The fact that there was no problem, doesn't mean it is the right thing to do. These "spiral wound" crush gaskets lose their integrity when compressed. They may come apart without showing clear evidence of that.
A crush gasket is supposed to compensate for irregularity in surfaces. Once you disassemble and remount, your irregularity may be in a different spot.

The Cometic gaskets are listed for a Yamaha application, I believe, but they are the same size as the ones listed by others for the Goldwing.

[cross]

Yes, i agree with that. I just called up Cometic and they told me that their Spiral Wound Exhaust Gaskets are graphite and stainless steel. Part number that fits our CBX is "EX651" off of Suzuki RM-Z250 2010-2013
He did mention that they are harder than the copper ones though
I went ahead and bought the ones from performance international

Tank you all for help

[daves79x]

Well, the proof of this all is - ‘do they leak’. I and many others have taken exhausts off and on a bike many times with the same gaskets in place and have had no leaks. I’m not all that interested in the engineering of the gaskets.

Dave

[Gearheadgregg]

I re-used the Copper and no leaks , BUT if changing to a complete different set of pipes i would replace with new gaskets JMHO

[cross]

I don't think that mine are leaking. But they are the old OEM ones and i'll be taking pipes of to clean them up and thought that hey may need replacing. Last time i took them them off i remember gaskets were were very thin