Erratic Tick Over

I have just put my bike back together after many months of waiting for the fabricator to finish the hardtail mod.s. I cleaned up the carbs over the winter and am now keen to tune the bike.

I have hit a few problems... firstly the YICS tool seals keep breaking on insertion, despite cleaning out the chamber and oiling the tool and chamber a bit. I have infact given up on it as the bike runs so badly when it is in I cant get it to stay running long enough to tune. Without it it the bike runs ok but I find setting the tickover speed to be nigh on impossible. As the bike warms up and I reduce the choke, it gets to a point where it either wants to cut out or I increase the idle speed and it gets to a nice level but then when I rev the engine it doesnt settle back to a nice idle, it starts revving very fast and I have to reduce the idle setting to get it back. Thinking maybe a sticky cable? Not the easiest things to get in the UK else I would simply change it and see if that helps.

Also when tuning, petrol leaks out of one carb through my pod filter. It stops if I put the petcock to on but I think it needs to be on prime when carb tuning? Is this indicating a sticky float valve?

Sorry, a few questions lumped in here....

Cheers,

 

It sounds like you have multiple issues. Start with addressing the fuel coming out the pod. You should be able to have your petcock in the prime (PRI) position with no fuel overflowing the carbs. In your case you are getting overflow which can only mean that your float needle is not doing its job (or your float - but this is unlikely). If you (or PO) have not done a carb rebuild recently then it sounds like you are in dire need of one.

Regarding the idle spiking - this can be caused by the a few things with the most likely culprit being either sticky slides or carbs being too far out of synch.

1) Rebuild carbs (You can do a COMPLETE carb rebuild for about $100 US dollars - I cannot stress enough how much this is recommended

2) Bench synch the carbs - this will give you a workable baseline for tuning once the rack is back on the bike

3) Wet set the fuel levels - this will ensure that (a) your floats and needles are doing their job properly and (b) you are not causing a too rich/lean condition out of the gate

4) Dynamic synch your carbs

5) Set your air/fuel mixtures

**NOTE: don't bother attempting #4 and #5 until you've done your valve clearances and adjusted your cam chain tension.

One step at a time...

 

The petcock needs to be on prime for maybe 15 seconds when the bike has sit for several weeks, or if you emptied the bowls for maintenance or adjustments.

The rest of the time, the petcock should be on "ON". However, your mistake enligthened the fact that you have a float that is set way too high or stuck.

 

Thanks guys.

So far I have completely striped down the carbs, ultrasonically cleaned and replaced the jets (upjetted too to try to make allowance for the pod filters). I had a donor set of carbs too so used some of the best bits from each including the float needles so could be that one wasn't as good as I thought!

I also re-shimmed the bike and set the cam chain tension so that one ticked off.

The carbs were visually set and I have also used a carb tuner. They look reasonably balanced now according to the device. Had to do this when the YICS tool out not in place. With the YICS tool in place the bike ran so bad I couln't keep her running long enough to tune.

So I have skipped the wet setting of fuel levels.... I am not sure how to go about that bit but will root around here....

Also pulled the plugs and no.2 looks sooty, the others look fairly clean. Listening to the way the bike is running, I am wondering if I am firing on three at times and then the forth is coming in more regularly and hence the bike ticks over at a much higher speed.

Does that lead me down any other avenues of investigation?

 

Next step, wet set your floats. It may solve your #2 cylinder problem. Is that the one fuel was coming out from in your pod?

 

Wet set your float height and I bet your problem will go away.

Wet setting is much more accurate than dry setting, although very tedious. Minute adjustments will make a big difference in float height.

To wet set you will need to have the carbs on the bench, leveled. Set up a fuel delivery system, then you will need a length of clear tubing to attach to the fuel drain on the float bowl. Then loosen the drain screw and fuel flows down the tube. Then just hold it to the float bowl and check the height.

If the height is off, drain the fuel, pull the bowl, adjust the ears on the float, re-assemble and start the process over.

 

Just when I thought I wouldn't have to see the inside of my carbs for a while!.....

Thanks for the directions guys, nice to know there is someone to talk to, feel like I am running out of steam after an electrical fault that took about 25 hours to find. Now I just want this thing running!

Actually the sooty plug wasn't on the leaking carb but then it doesn't leak when the bike is running, only when off when I left in prime. I thought I remembered it had to be in prime when tuning but must have made that up.

 

Just found this tip which sounds like it describes my idle issue:

If you can't get it to idle, or rather the idle stays real high then drops off and dies, check for an air leak at the carb manifold. Squirt some gas or starting fluid on the manifold and see if the revs change. If they do, you have a leak.

Nice little article: http://www.dansmc.com/carbs.htm

Another thing to check!

 

I'd say it was a posibility if not for that leaking carb

 

Wet-set float levels: http://www.xj4ever.com/setting%20fuel%20levels.pdf

You can't skip anything.

 

Christ that was a horrible job! Took me seven iterations!

I couldn't figure out how to measure the float height so just did it trial and error.

Found a horrible surprise in carb two... one of the pillars that support the float pin is cracked. I must have done it previously but it didn't show. Now it is obvious. Somehow it seems to be holding up despite looking like it is cracked right through.

I have a second donor rack of carbs that I guess I will have to break up and swap one at some point. Hoping that can wait till the winter now. Really tried to avoid breaking the rack apart when cleaning up as it sounds a pig to get re-aligned.

Ran out of time tonight to properly test the bike again but quickly tried to start her and no joy. I'll put the battery on charge over night and try again with a topped up battery.

Put the carbs on and set petcock to prime and nothing leaked out so maybe that issue is resolved. Carb one and two were showing about 8mm over the float bowl so guess that was enough to have it spilling out.

Thanks for your help guys, me thinks I'll be back with more issues very soon!

 

DON'T be afraid to break the rack on account of any alignment issues upon reassembly - I assure you it is mostly FUD (Fear, Uncertainty, and Doubt). If you don't own a manual impact wrench go to your local Harbor Freight (or equivalent) and get one - they aren't much. That tool will pay for itself in short time either way. The rack rail will take care of the majority of the alignment concerns - just be sure to reassemble your rack on a flat, inflexible surface (sorry for the smell of carb cleaner on the kitchen table darling ;-). Once upon a time I was leery of breaking carb racks too - now I (an others who've done it) just giggle at the thought that I once was nervous to do so. If you take your time, don't skip steps, and do a full, complete rebuild (ZESTFULLY clean and all new rubber including throttle shaft seals) you too will join the club of motorcycle owners that do their own work and can be proud of the results!!

 

Great to hear, I am not going to have much choice, that pillar is definately on it's least legs err leg!

Going to try to put it off for the moment as it seems to be holding the pin in place.

Right, carbs back on the bike and all eager to get going but the bike wont start now! Not giving the slightest signal that she is close to firing up

Any magic tricks anyone?

 

http://www.yamaha-triples.org/workshop/ ... Repair.pdf


http://www.xjbikes.com/Forums/viewtopic ... +post.html

Starting:

Hook it up to a car battery and/or pour a small bit of juice down the plug holes

 

I think a bit of epoxy weld I can handle but fabricating a new pillar is way outta my league guys! Neither the tools or experience for that job. All respect to those that can, amazing work.

Going to try again later to start her, let you know how I get on!

 

I bet Dave (hogfiddles) might have a carb body laying around rather than trying to engineer one.

 

Cheers Lanker but I have a donor rack of carbs that I can pull one from.

Out of interest, anyone ever tried to do their own ultrasonic carb cleaning? The service is quiet expensive in the UK so I decided to buy a tank that can just about hold my rack (I didn't split the rack it to clean them and looked for a fluid that was rubber safe). I was really impressed by the results but now I am noticing accelerated corrosion on the parts, particularly screws and deposits building on the casing (looks like salt marks). I think I did a couple of rinse cleans but now can't remember. Little worried about the corrosion but guess that anything inside will be getting flushed out.

 

I've only ever done it one way - that is, split the rack, remove EVERYTHING leaving only the carb bodies and bowls, and soak them 2 at a time in a gallon pail of carb dip like this (http://www.pepboys.com/product/details/ ... quantity=1) for 24-48 hours depending on the condition along with the emulsion tube and jets. Upon taking them out I blow out every passageway with compressed air then rinse in hot water thoroughly and repeat. Fit with new rubber and gaskets. Works like a charm every time.