Front cylinders take a few minutes to warm exhausts

Hi everyone, I have a single seat sandrail with a 1985 vf1000r motor. Motor has not starts for around 8 years. I just started it up last week, and it seems to runs very well, but I have a question:

I have four exhaust pipes and the 2 rear cylinders pipes gets hot fast, but the the 2 others, the front cylinders stay colder and warm up only after like 5 minutes, and when at idle do not push as much air as the 2 others, but when you push throttle down they all seam to work well. So is it normal or am I having a front cylinders problem? And what can it be (this is the vfr with only one cdi box. Thank you in advance. It does not seem to puke gas through these exhausts,

 

Do a compression test? Check the spark plugs? All kinds of things.

 

yes it was my next move

I am going to check compression when I come back from work today, plugs are new but I will check them again to see how they look like, actually I checked one yesterday and it was black but ok, which just remind me that I saw that spark plug caps were like from a 2 strokes dirt bike on the 2 cylinders that are not working properly, from what I remember caps have some type of resistor in them, maybe that is my problem???
thanx

 

Sounds like those 2 cylinders are not firing at idle, for any number of reasons. Determine whether they are missing fuel, spark, or air.
So you don't smell a bunch of unburnt fuel? Is it backfiring and shooting flames out of the exhaust when revved a bit?

 

No it sounds great when I rev it, the only thing I saw was some unburnt fuel when I started it up Sunday, but it wa because I left the fuel pump on too long after it stopped.

 

Does it feel low on power when you accelerate?

 

May need a carb clean with extra attention to the pilot jets.

 

HI there and thanx for help, I don't know because it is in a sandrail that I got as a project over the summer. I actually never drove it for real, I only started it up and warm it up in my garage. It is not street legal and down here in az I have to drive like one hr to even get to a place where it is legal to drive it. But from running it in my garage not under load it seems real strong, lound and mean as it gets, but offcourse it can be another story under load. I have a 4 days break in 10 days I will for sure try it then. Could it be simply a carb synchro? 2 rear cylinders gets real hot but front ones do get hot preaty hot but not as hot as rear ones. I checked jets and pilots on all carbs 3 times. The only thing I can think of is that the pilot passage in cylinder 2 and 4 is slightly obstructed so it is running only at 75% of its capacity? I will take carbs apart on Thursday. I also need to get a fitting for my compression gauge to check cyl 2 and 4 compression, but both at the same time does not seem right. Thanx anyway I will let you knoe

 

I checked pilot jets and they were ok, though it seems that pilot jet carb passage was not has good as the 2 other cylinders, but it was not bad at all, it might just be that and sbecause of it these 2 cylinders are running with less gas while idling. But then when I use throttle they work normally because not using jet passage anymore? I am going to take carbs right now and let you know, thanx

 

After checking carb again, I saw that cyl 2 and 4 carbs were not letting as much in as cyl 1 and 3. So I adjusted carb linkage to let as much air ar others. I did not start it because it was late but will do real soon

 

check the floats. do a carb sync.

 

Hi there, and thank you for your help, i checked float many times and it is good. Yesterday i adjusted each carb linkage because front cylinders were not firing at 100%. so i open them up a little for more air. and then i started it up and front cylinders ran strong real strong, but now on the rear cylinder i have one that is not running at all??? i am going to re adjust the linkage and check spark plug cable and caps, they seem shot,

 

Yeah you already said that. Do you know what a carb sync is? Like with this tool:




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yes I know what it is, but I don't have one and I am not sure I have cash for it, depends on price and I don't know where to get it. this afternoon I fiddle with linkage and got 3 out of 4 cylinders running properly. I just can not get last one, lol. the thing is I am not sure where you actually align carb valve with holes. there are 4 of them and manual says to the edge of it but which ones??? its a diamond patterns like baseball bases, but I am not sure to which one I need to align it to? I am getting closer, one thing I know though is that I can take off and put back on carbs under 2 minutes now after doing it 30 times, lolololol, and I am lol because I had a few beers since. This is the first time I see a carb setup that corky and I have done Porsche 914 quad del ortho racing setup and many weird car setup, but this setup is tricky to get correct without the gauge. Any tip on the carb valve alignment with holes? Thanx in advance, it is never easy to get engine running after 15 years in storage.

 

Without an actual vacuum tester, you are basically tuning in the dark by candle light. You are wasting your time, is your time worth $75?

http://www.ebay.com/itm/like/380985091328?ul_noapp=true&chn=ps&lpid=82

 

I agree with you, but I am not bad at it and done it for years. Right now I am trying to get it baseline enough on all 4 carbs to have a base. My time is worth way more than $75 hr, but I do racing to relax and always try to keep it with what i have to keep my budget under control because I race 3 diff categories from single seat ultra light to FM and shifter kart. It adds up after a while. I could not find a 4 cylinders gauge like that where I live. Can I use a single compression gauge on it and adjust them one after the other? Thank you in advance.

 

No, not effectively at least, you can't adjust them one at a time. As you correct one, the other 3 will be changing. You will be chasing your self around in circles for ever.

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