Look as I see it this is a forum where we help each other....I am a retired U.S. Marine living in Thailand but when I send a topic in I get the typical answers like LOOK AT THE DATA PLATE I am not stupid and I hope anyone that uses a computer is not this stupid...I have no Data Plate.... I believe my bike is a 1982 Yamaha XJ750 Special. I need to get rings and now my mechanic here in Thailand tells me to get the 1st O/S rings and Pistons... Can anyone help me.

My bike after about 150KMs starts missing, I can change the number 4 plug and I am good for another 150 kms..


I have previous post with my engine and frame numbers posted...


KHUNDAN sends

I completely understand your frustration. Sites like this one seem to attract people who want to lord their "superiority" over others, rather than provide fraternal support to others who share their interest. Imagine what a sorry life must be behind those whose great joy is being the big man on the forum site...

In any case, not exactly sure what help you're asking for. If you're looking for the best way to id the model year of the bike, other than with the id plate or engine #, I'm not sure what to suggest. Fortunately, there isn't a whole lot of variation in the early model years, so your likelihood of getting the right parts is high, even if you're off by a year.

I've ordered a fair amount of parts through Bikebandit. It occurs to me that by looking at the parts schematics and comparing them to your own engine, you may get a higher degree of confidence as to what model year bike you have. Order rings from Bikebandit based on your assumed model year... Sorry I can't be more help than that.

In regards to the engine missing, I have had similar experience and have read of others like us. It seems the #4 is the most likely to have this problem, which seems to arise from air intake leaks giving too much oxygen to the fuel mix. My own problem seems to stem from bad carb boots, although I am still in the infancy of adjusting/synching the carbs, so it could be a maladjustment issue too.

Do you have the Haynes manuel for 80-84 Secas?? Mine sure makes it look like they were all the same, which is what I'm basing my opinion on. If you have a question I can answer by looking it up there, let me know and I'll do my best.

Good luck, and by the way, from someone who's never served, thanks very much for protecting our country, Marine.

Well, I'm glad I read this before I posted on your other topic.

As the only person that replied to your first post then I'll assume that your comments are directed at me.

Had you the foresight to state in your original post that there was no data plate then the response would have been different. You ask for help without supplying all the information then the responses are going to get may well state the obvious.

As for a reply to your ring problem I have several worthy suggestions which need to be checked before considering oversize on std pistons. However, for fear of sounding stupid, I will not impart my knowledge as you most likely already know the answer.

As an ex marine, you should know better than shooting yourself in the foot.

Helping with knowledge gained from personal experience is voluntary, Appreciating knowledge passed whether valuable or not is compulsory IMO.

Even JBCahill's quote

indicative of the question asked.

Cheers HG

If you can give me the engine # I can probably help you. They are all listed on the CD, make model and year.

Is it apart? Have they checked the compression yet? If it is the rings adding a few drops of oil and run another compression check should make it rise some. Intake boots are availible aftermarket if you need them.

I realize I was wrong by the post that I sent, and hope that all will let by gones be by gones. I was not thinking and was pissed that my bike is not what it was before.

Sorry if I upset anyone as I am the one that was wrong. Thanks for having the courage and respect to call me on it...

Here's the rest of the story:

BIKE 1982 Yamaha XJ750 (Pretty Sure)

Problem: After I ride it for about 150 Kms even if it's not all at once, when it gets around 150 kms it starts missing badly.

I can take the number 4 plug out and clean it and then it will run fine for another 150 kms.

I took it to a Thai that works on big bikes and he told me the rings were bad on that cyclinder and it was fouling the plug.

The bike has new Carb rubber mounts (Probaly less than a year old)

It runs great and strong until I get about 150 kms and have to either clean or replace the plug on the number 4 cyclinder.

I never see smoke from the exhaust and the plug looks to have carbon instead of oil in it to me but he says it's being fouled by the rings on the number 4 cyclinder.

I may end up getting a couple of plugs and riding it to a bigger city and have someone else look at it before I start ordering parts etc..

Thanks to all and sorry I always seem to never give enough info or ask the right questions.

Hi KHUNDAN,

Did the mechanic run a compression check on #4? How did it compare with the other cylinders? It could be anothe type of problem causing the fouling. let us know.

Winterhawk,
No the mechanic here did not run any compression test as this is Thailand and I'm in the northeast so the most they have here is channel locks and clothes hangers and of course welders....


No these really are some back woods mechanics but most of the time they do pretty good. But I think I need to go to Korat and have a real bike mechanic check my bike out.

Thanks forthe replys.

Winterhawk,
No the mechanic here did not run any compression test as this is Thailand and I'm in the northeast so the most they have here is channel locks and clothes hangers and of course welders....


No these really are some back woods mechanics but most of the time they do pretty good. But I think I need to go to Korat and have a real bike mechanic check my bike out.

Thanks for the replys.

KHUNDAN,

Just a couple of things to check prior to tearing the top end apart:

1. Are you burining oil?? ie do you need to add oil to the crank case to keep the level up?

2. Does the #4 plug foul when cruising at highway speeds? Or, does this tend to happen
when you are "plodding" along in city traffic?

There is a possibility that #4 cylinder has an overly rich pilot setting.

Kliph

I have never had to add oil. I change it always at about every 2000 - 2500 KMS, I added and oil cooler about 3 years ago.

I firmly believe myself that I dont have a ring problem but something else. Today I am taking my bike to Burirum to a friend (Thai) who builds bikes and drop it off for him to keep and look at.

I think it's in the carbs myself. Or if a seal or gasket could be leaking I dont know and this is the first time I've had problems with this bike. I love it and don't want to have to junk it or sell it.

The Thai's say this bike is a Yamha XJ750 Special probaly of a 1982 year.

It's crazy to me, I can ride it hard or easy nd still between 140-150 kms it starts missing and I have to clean the No#4 plug. Then it's good to go for another 150 kms.

However since I have to ride it to Burirum today, I took the plgs out and No#3 and No#4 were alittle dirty but No#1 and 2 looked new. So I'm taking the old plugs with me so the mechanic cn look at them.

I will keep all posted on this as it has me baffled.

I have worked on automobile engines before but not on bikes much.

Thanks for everyones post and reply's and ignore me if sometimes I seem arogant or stupid..

Thanks

KHUNDAN you may want to check out http://www.bikepics.com/yamaha/ and see if you can match up your bike to one of the XJ models. Something may stick out. For example the engine guards on the XJ650 maxim are a few inches longer because the engine is a little bit smaller. I made the mistake of buying XJ650 engine guards for my XJ750 and they stick out a little to much for my likening because of the longer engine. It’s worth a look. Or better yet you can post your picture on there site for free.