1st off, Hi all, new to the board.

Here's my problem. '82 XJ750 Maxim. Bike sat 9 months with a tank of gas in it. I drained the tank and carbs, added fresh with some seafoam, and wouldn't start. I pulled the carbs, cleaned and installed the K&L kits. Seat was different than the original but used it anyway. The fiber washer was thinner and caused the float to be at a different level than original. I changed back to the brass washer under the seat and got the float level back to where it was.

New air filter and carbs on, the bike would barley run. I pulled the plugs and they were all way to rich. Reset the mixture screws to 3 turns out. Bike started but ran rough and wouldn't idle. Read plugs again, 2,3,4 are lean, 1 is rich. Restart and adjust screws till it would idle.

Test ride, at 3000 rpm, it misses bad and backfire on decel. 2.3.4 still lean, 1 is still rich. Reset all at 3 turns, will not start again.

I'm pulling my hair out here

shot ether around the the carbs and holders, no effect, so that is good.

I don't need it running perfect, just to start and ride decent by thursday.

Any help appreciated.

Thanks

Sounds like you are doing all the right things, just not with the right results yet.

I would also suspect carbs even still, that's just where my logic would take me given the way it's running, but you might check out the "Help with diagnosis s.v.p." post below. That bike had the same situation with the plugs and similar running issues. A new set of the proper plugs cleared it all up.

One thing you might try (shotgun troubleshooting!) is when it's missing/crapping out - spritz a little either into the air box and see what the result is. If it smooths out then you know you are running lean, if it gets worse then you know you are running rich. If you get no substancial change then it is likely an ignition problem.

Thanks for the reply

The plugs are new NGK BP7ES (That's what was in it and what the NGK book called for). I'll try the either as soon as I get it started again. Right now it won't start. I can pull the plugs, dry them and it will fire, start, then die. It idles just for about 5 seconds then dies. I try to get the rpm up, but giving it gas kills it, as does the choke. The plugs are always wet (gas) when removed. I'm not getting leakage into the carb holders, so I suspect the floats are working.

I put 87 oct. in, going to drain and fill with 93 oct. to see if that helps.

If i can just get it to start and run, I can do some tuning.

Roger that. Let us know what happens.

Put original seats back in. Used the new needles because the old ones had grooves from the seat on them (not dirt, a mushroomed look near the tips where they seat).

I adjusted the butterflys so all of them were in the same position. Just a hair off closed (bench sync I think you call it)

Starts but won't idle below 2500 rpm. Below 2500 rpm it just dies but will start right back up. Sprayed either all over and no change, no increase or decrease in rpm.

I'm not familiar with the hitachi carbs (I've always owned honda's, this is my 1st yamaha). Idle circuit?

Any thoughts, comments or bashings welcome

I had to take my bowls off and clean the idle jets 4 times before I got my bike to run right, they kept getting clogged up by residual junk from who knows where. I'd double check'em just to be sure.

- check your float levels
- check the resistance of your coils
- check the gap of the plugs
- have a beer
- drain one of your bowls into a glass jar. Look for rust or debris. Carbs might be plugged.

When it's running..
- buy yourself a carbtuneII to set your mixtures. Costs around $50USD.
- balance the carbs
- have another beer.

- BTW - it costs $100 lest to buy Carbsticks, Mike's YICS tool, the XJ3.0 CD, and a Colortune set than it does to have a bike mechanic fix your 'no start'.

:)

RedRider,

When I first got my XJ550, it had sat at the previous owners house for YEARS. I swear I dismantled the carbs at least ten times before I could get it running worth anything.

Do you have any gas in the oil? My carbs are Mikunis, whereas yours are Hitachis (little disclaimer there), but since you mentioned you removed the needle seats, do yours have o-rings under the seats, or just the sealing washers? I had gasoline leaking by the o-rings and basically flooding it out.

Maverick

My bike bike would not run or ran rough when the petcock was set to On or Res (reserve).

The vacuum hose responsible for opening the petcock when the petcock was set to On or Res, and the bike was running or trying to start, was severely cracked.

When I set the petcock to Pri (for Prime the carbs - petcock open all the time) the bike would run, but ran rough.

I went to an autoparts store and bought some vacuum hose to replace the one that ran from the petcock to the opening between the carb and cylinder. Now the bike runs when the petcock is set to On or Res.

Also, you may want to remove the tank and remove and clean all the contacts on the coils. Test the coils according to the repair manual, but unscrew the spark plug caps before testing, as they are resistor caps and interfere with the resistance reading on your volt ohm meter. These bikes are really picky about electricity, so it would be a good idea to clean every electrical connection you can get to.

Lastly, when I bought my bike my carbs were so nasty they required 48 hours of soaking and scrubbing before all the gunk was removed.

Instead of checking float levels you should really be checking FUEL levels.
I think it should be +/- 3mm off the bowl center line.

Mike