If the revs are staying high since you took out the carbs I'd be thinking the carbs might not be seated fully and there might be a vacuum leak. You could spray some wd40 around the intake area and listen for a change in revs. I'd also check that the throttle cable is routed correctly, that it's not adjusted too tight and that it snaps back properly when you release the grip. Also check that the choke plungers are all returning properly.I'd agree with bazza the ht caps are a possible problem. They're a common failure and can cause a misfire. You could try spraying some water around the caps while the bike is running and listen if the engine stumbles. You can also run the bike in the dark and look for arcing. Another trick is put water on the exhaust headers and see if one header dries slower than the rest, that can show a cylinder that's not running properly. The ngks caps are very cheap so worth replacing anyway. If the bike has been running badly for a good while I'd take out the spark plugs and inspect them, clean them off and see if that helps. If they're very bad I'd replace them. I haven't had TPS problems so I'm not sure what symptoms from that are but I know darrsi has had trouble with his so it's worth checking if he says so. Another possibility, Red98 had serious problems trying to solve a stutter, he rebuilt half the bike trying to find fix it and it turned out to be a bad reg/rec so that could be worth checking.I'd start by ruling out those problems one at a time because they're the easiest. If you're confident all those things are good then look at the carbs. As a quick test on the carbs you could try leaving the choke on a bit and ride the bike. If the symptoms improve then it would point to the problem being a lack of fuel from the carbs.
Quote from: His Dudeness on 16 January 2020, 06:53:01 pmIf the revs are staying high since you took out the carbs I'd be thinking the carbs might not be seated fully and there might be a vacuum leak. You could spray some wd40 around the intake area and listen for a change in revs. I'd also check that the throttle cable is routed correctly, that it's not adjusted too tight and that it snaps back properly when you release the grip. Also check that the choke plungers are all returning properly.I'd agree with bazza the ht caps are a possible problem. They're a common failure and can cause a misfire. You could try spraying some water around the caps while the bike is running and listen if the engine stumbles. You can also run the bike in the dark and look for arcing. Another trick is put water on the exhaust headers and see if one header dries slower than the rest, that can show a cylinder that's not running properly. The ngks caps are very cheap so worth replacing anyway. If the bike has been running badly for a good while I'd take out the spark plugs and inspect them, clean them off and see if that helps. If they're very bad I'd replace them. I haven't had TPS problems so I'm not sure what symptoms from that are but I know darrsi has had trouble with his so it's worth checking if he says so. Another possibility, Red98 had serious problems trying to solve a stutter, he rebuilt half the bike trying to find fix it and it turned out to be a bad reg/rec so that could be worth checking.I'd start by ruling out those problems one at a time because they're the easiest. If you're confident all those things are good then look at the carbs. As a quick test on the carbs you could try leaving the choke on a bit and ride the bike. If the symptoms improve then it would point to the problem being a lack of fuel from the carbs. well said DUDE, some great advice there
Cheers for all the advice.I've previously checked the TPS and it seems ok, well within the ranges, may need a little adjustment to make it exact. Think its just over the 5000 rpm mark.Think I've made some head way.A mate said to try a compression test on the cylinders. All cylinders are coming in very low, about 2/3rds down on compression around 4kg/cm2 instead of 12 to 15kg/cm2To me this is corresponding to the carbs when i tried balanced them and they were also coming in at a lower range to the books.If this is the valves/piston rings has anyone else had these done recently? I will check out all the other suggestions as well first, but looking at how much a garage will charge to fix this?Would like to do it myself to save the labor charges but the girlfriend won't be happy with me being in the garage for a week or two.Wondering if its worth fixing or moving on to something else. Cheers
Are the carb rubbers in good condition?Yes they seem all ok, I've double checked all the screw clips holding all the rubbers to the carbs on both sides, all tight
If the engine is only pulling 150Hg there's something very wrong with the pilot circuit probably the screw setting. Unless you can get the intake vacuum between 230 - 250mmHg you're never going to set the carbs up correctly and the bike will run like a dog.I suggest you recheck each carb and what you've or I think you said mate put in and how.
The butterfly's being open more will increase the Hg reading, these should only be open when the throttle is twisted. With the throttle fully home the Hg reading is set via the pilot circuit only, each must be between 230- 250mmHg at between 1150 - 1250rpm, if the reading is too high the butterfly isn't in it's rest position. This could be due to a number of factors, bad assembly, worn/broken part/s or incorrect previous carb balancing.I my experience most owners and many stealers don't know how to balance crabs, they go straight for the butterfly screws when it's the pilot circuit that's the issue. As I stated unless they're all pulling min/max of 230- 250mmHg with the butterfly's at rest you're wasting your time. The other real big mistake onwers/stealers make is moving the TPS, this is set at the factory and it doesn't move (unless it's faulty) in operation it's a datum. They test it, it's reading over/under and they move it, that's it the datum is moved, the reason it's out (and it only works on the one carb No4) is because the butterfly/linkage has moved/worn, so no longer aligning with the datum. It's the butterfly/linkage that needs bring back to the datum, by resetting them, i.e. level of Hg, then balance all the others, 4-3 then 1-2 then 1-2 & 3- 4. Just about every TPS has been moved and in my experience just about every bike I've worked on the carbs are out of balance!