Topic: Snapped off accelerator pump nozzle

[DaysGone]

Hey guys, any idea where to get a replacement nozzle for an accelerator pump outlet on a 1980 CB650 C, or dimensions on an original so that I can try to fabricate my own? Maybe ideas on how to swap it out? Someone who owned the bike before me managed to break one of them off, and now it loses power when the throttle is opened because the pump isn't working properly. It's the carb that has a rod linking the throttle controls on each of the 4 carbs. Let me know if you need any more info to clarify.

Thanks!

[Flyin900]

Replacement carb body for that issue if it is the brass tube inside the carb throat that has been broken off. No way to really repair or even replace the part given the spot where it is and the orientation of the tube into the carb body.

[goodtryer]

Are any of these what you are looking for: https://4into1.com/search.php?search_query=accelerator%20pump&section=product

[DaysGone]

Yeah Flyin, I think I got one of them out at one point, but they definitely are difficult to get to. And yes, it is the little brass tube inside the carb on the air side.

No Goodtryer, none of those will work. That's the pump itself, I'm looking for the little nozzles that are inside each carb in front of the choke plate. On mine anyway, there's a little hole in the choke plate where I would imagine the fuel is supposed to be able to pass through when the pump is actuated.

I talked to my mechanic some more, and apparently when I open the throttle, three of the cylinders are being starved of fuel, and the fourth is getting flooded because all the fuel is going out the snapped off nozzle. Luckily, he says there are some possible workarounds. Apparently, before accelerator pumps were a thing, bikes just ran a little rich at idle. He suggested advancing the timing a hair or possibly going up a jet size on the idle jet, so I'll give that a shot and let you guys know how it goes.

PS, He also mentioned that it might run better with some mufflers on it, someone before me chopped them off. Anyone know of some decent mufflers I could look into? I'd prefer something not chrome.

Thanks guys!

[Flyin900]

The correct way to repair is replace that carb with another unit. You can sometimes find single units on EBay for reasonable money. It isn't too difficult to break down the carb bank and remove and insert a new carb. A proper Honda shop manual is a must if your not experienced on carb work; even if you are proficient it is a good resource to download off this site.

What your mechanic is suggesting is really sketchy, yet may work somewhat. The issue I see being an experienced carb rebuilder is there will likely be issues in getting the right size jets to function well in this work around. You end up pulling the carbs numerous times to re jet and test for better running conditions; this is just too much work IMO for an unknown result.

You will only need to break down the left side of the carb bank, as the accelerator pump circuit is on carb #2. It would be a few hours work for an experienced carb guy or your mechanic, if your not able to do this work.

No mufflers are no good and some cheap ones are better than straight pipes, your likely running lean anyway with straight pipes. Spray with black BBQ paint if you don't want chrome.

[grcamna2]

Has anyone tried removing the choke butterflies and shafts and then trying to remove those small,brass spigot/jets? Those little pieces get clogged-up fairly easy which certainly leans those 'keyhole' carbs out too much;it would be a handy thing if those brass jets/spigots were removable so they could be cleaned/replaced,then reinstalled for much better carb. performance.

[Flyin900]

Not going to happen as they are likely a swedge fit and difficult to get to in there without damaging the part trying to pull it out. When you damage the part how do you find a replacement?

I use a combination of Ultrasonic, carb cleaner directly into the accelerator pump passages and most times it opens yet doesn't completely clean out the brass nozzles. I invested in a hand held steam cleaner and shoot live steam and alternate with carb cleaner to ensure those passages are 100% new vs the 30-50% average you will normally get from gunked up ones.

I wrote another post on this exact subject, as I have struggled over the years with the same issue. The 30-50% clean brass nozzles while they now work still create hard starting issues with the CV series carbs and weird running issues too.

How does a inexperienced rebuilder know when those brass tubes are 100% vs 50% clean???

[grcamna2]

Not going to happen as they are likely a swedge fit and difficult to get to in there without damaging the part trying to pull it out. When you damage the part how do you find a replacement?

I use a combination of Ultrasonic, carb cleaner directly into the accelerator pump passages and most times it opens yet doesn't completely clean out the brass nozzles. I invested in a hand held steam cleaner and shoot live steam and alternate with carb cleaner to ensure those passages are 100% new vs the 30-50% average you will normally get from gunked up ones.

I wrote another post on this exact subject, as I have struggled over the years with the same issue. The 30-50% clean brass nozzles while they now work still create hard starting issues with the CV series carbs and weird running issues too.

How does a inexperienced rebuilder know when those brass tubes are 100% vs 50% clean???

A swedge fit,ok I imagine that means they were designed to not be removable.. I have shot lots of Gumout through all 4 of them,then back-flushed and tested and got all 4 of them squirting cleanly again:it certainly took a Long time and Lot's of carb cleaner.I would have hoped that Keihin had made replacement nozzles for those as it's So Easy to get them clogged.

[DaysGone]

Flyin, I definitely understand where you're coming from about swapping jets out being to much work, but at the same time, I've pulled those things to clean and swap jets so many time, it's just about second nature by now, haha. And of course, one of my carbs has started leaking out of the float bowl rim, so I'll be pulling the carbs to look at that anyway. Anyone else ever run into the issue of your new gaskets being so oversized as to be nearly impossible to get installed properly? I'm pretty sure I pinched the gasket on one or two bowls trying to install them.

As for buying new individual carbs, and replacing one of them, I've looked and haven't found anything, but I'm definitely planning to keep an eye out. In the meantime, I'll settle for a workaround. Also, I'm hoping that I'll only have to go up one jet to get better performance. I'm going to try the timing first, then the jets, then a combination and see what happens. Lots of work, but hey, working on it is half the fun! That's what project bikes are for!

Thanks for the tip on the mufflers, I'll have to give the bbq paint a try. Do you think that would work on my headers too? I found these mufflers, might end up ordering them. I want to do a 4 into 2 setup, 4 mufflers back there seems like a lot. I'm guessing I should probably get the biggest ones if I'm planning to route two headers into one muffler? The other option I'm considering is just getting some super cheap ones off of Amazon, but these seem like good quality.
https://purposebuiltmoto.com/product/torpedo-muffler/

[TwoTired]

I would do my utmost to make the accelerator pump system work.  It would be tedious, but one could be made from a lump of brass rod, copying dimensions from one of the other carb positions.   One thing the evades many is the pump's fuel rail between carbs has restrictors inside the rubber couplers.  This makes the pressure at each nozzle even for equal shots into the carb throat.  If you replace the rubber without those restrictors, the pump system will never work as intended.  And squirters farther from the pump will have weaker spray patterns.

Without the accel pump, you will not be able to whack the throttle full open at any engine RPM.  The carbs will go lean and the engine will just wheeze at you.    You'll have to find and over-rich idle setting, (and possibly main jet needle setting) that will allow, 1/2 throttle twists and then open the throttle more as the engine pick up RPM.

Cheers,

[grcamna2]

I would do my utmost to make the accelerator pump system work.  It would be tedious, but one could be made from a lump of brass rod, copying dimensions from one of the other carb positions.   One thing the evades many is the pump's fuel rail between carbs has restrictors inside the rubber couplers.  This makes the pressure at each nozzle even for equal shots into the carb throat.  If you replace the rubber without those restrictors, the pump system will never work as intended.  And squirters farther from the pump will have weaker spray patterns.

Without the accel pump, you will not be able to whack the throttle full open at any engine RPM.  The carbs will go lean and the engine will just wheeze at you.    You'll have to find and over-rich idle setting, (and possibly main jet needle setting) that will allow, 1/2 throttle twists and then open the throttle more as the engine pick up RPM.

Cheers,

TT,I've never removed the rubber fuel rail hoses and I don't want to mix them up with the restrictors in them;I imagine that each one has a different size restrictor.Can you tell me if the restrictors are damaged by strong carb cleaner? I might just leave them all connected when cleaning that system with carb cleaner spray?

[TwoTired]

The restrictors are metal tubes inside the rubber.  Carb cleaner won't hurt those, but some carb cleaners attack the rubber.  In fact, the good effective carb cleaners certainly will.  But, some states won't allow mere citizens to buy it.  So, there's that.

To maintain pressure in a flowing tube, the tube must get smaller in diameter as it gets further from the source pressure.

Cheers,