I need some help getting my sons first bike going!!!!

Hello everyone. My son just showed up with a big smile and a beat up 83 750 maxim. Im having trouble finding a plug or any mention of it in any manual. Its on the left side of the head towards the back but still on the side. Any leads would be greatly appreciated. Thanks

 

I think that is the YICS channel and should have plug in it. ( there should be a plug on the other side also.). It is where the YICS tool goes when using it to synchronize the carbs. It has to be plugged for the bike to run. If that is what it is then you might be able to remove the one on the other side and match it at your local hardware store. If no, contact Chacal and he will have the correct part. Click upper right hand link.

 

That's not the YICS port... This is:



Image taken from xj4ever.com and the "how to" instructions for the YICS blanking tool.

I'm guessing the plug that is missing is one that is put there permanently (or supposed to be permanent) after milling the head during manufacturing... but that's just a guess based on how carbs are drilled, then plugged with brass...

 

The missing plug is an oil gallery plug. Should never come out! Have a machinist make one and Jb weld it in place. Factory was a press fit. Other fix is pipe thread 1/4” or 3/8” and a brass pipe plug with P51 pipe thread sealant oil and fuel proof.

 

Someone did a hack job , do as Toomanybikes suggested, and DO NOT run till that is fixed . Cheers.

 

Ok, thank you very much. If i cant get it to seal with a pipe plug, then it a good thing used heads are fairly cheap. Thanks again!!!

 

Another note i should add, i can see that the valve spring behind the plug is broken. I would guess that is what knocked the plug out. Now im thinking i will just find a used head for it. Thanks again everyone

 

Heres a pic. The spot that looks like sludge is the broken end of the spring. Hard to get a good pic

 

Wow, interesting, thanks for sharing this.

 

You have discovered a very unusual failure.

 

Yes like how did the valve spring get inside cylinder? Pull valve cover and investigate !!! and include pictures !!

 

Please make sure you buy a complete used head if you have to go that route. Cam shims and clearance can be a pain to sort out if you start mix-matching head parts. Unfortunately I know first-hand from my engine rebuild.

 

Thanks for the advice.

 

I pulled the valve cover and there is nothing unusual to report. Not sure why the spring broke. Im waiting for my son to get some time to pull the head and cylinder. Like i said, its his first bike and he is excited to put some wrenched to it

 

some times the plug came as a bolt from factory. tou could tap the hole and put a bolt in the hole. grease on the tap to collect chips

 

That looks like a pic of the right side of the head. Mine has that bolt on it. The plug is on the left side. Thanks though

 

some motors have all plugs some have the bolt on left or right side it was some sort of factory fix

 

Just my $.02
New to this engine, but I've torn a few down. If you are SURE that spring is broken, and not just the end of the spring (Hard for me to tell in that picture), that's a whole tear down to me. Or at least head off and hand turn the engine with bright lights and a magnet.

There can be pieces of spring steel down in the cylinder...
It would be like having ring pieces in there.

I have an 83 750 maxim parts bike... but I've never even turned it over yet. I don't know if the head is that good or not...

 

Yes, lots of assholes have messed up good engines. lol

 

I can definitely see the end of the spring where its broke. I tried to get a good clear pic, but the small hole and lighting not working out. And yes, the head will come off. Im not new wrenching on bikes, ive rebuilt plenty of harleys. And know how fast rebuilding a motor can add up. Since its my 16 year old sons bike, i want to keep the cost down and make sure it is reliable for him.

 

Heres a better pic

 

From what i can see of the piston through the spark plug hole, there is no marks or damage

 

Oh yeah, that's broken

 

The only way for the spring to get into the cylinder , is the spring went though the base of the head . The valve is inserted into the valve guide ,the spring goes over the stem and the spacer and keepers , the spring is not in the combustion chamber. This is simplified idea of what it should look like.

 

the spring is in the oil gally isn't it? not in the cylinder correct?

 

Looks that way. I have extra 650 springs, valves, buckets and keepers from a head I bought by accident. Pay postage and I will send it. I also have a bunch of the same sized shims I can't use on the 550.

 

Thank you very much for the offer. I have a possible line up for a head. If it falls through i will take you up on it.

 

Can anyone tell me how these studs are fastend? Threaded, pressed? This one got bent during shipping. Thanks

 

They are threaded.
Try tightening two nuts up against each other on the thread you can see and then undo the stud with the lower of the two nuts.
Drop a ring spanner over the stud first and use that to get purchase on the lower nut.

 

its in a good location to apply some heat to it before you try.

 

Did the studs bend while you were trying to extract them?
Heat, care, and patience need to be used so you don't damage the casting. I'm surprised that it hasn't cracked already.

You might wnat to use a good set of vice grips down-low on the worse of the two so it won't try to walk out in an oval and bend more (or damage the threads). If you can weld, stick a length of bar to it to break it loose, then cut the bar off and continue with a wrench.

 

Thanks for the input. I was able to get it out with a channel locks. It bent during shipping. Ill have to double nut the one on the head i removed from the bike and replace it. Thanks again.

 

Oh yeah!! what the heck was I thinking...
Don't know why, I was picturing spring in the gas path, pretty silly. I can't think of an engine that would, must have been pretty tired that day or was thinking of stem pieces somehow.

 

I don't understand how it got into that passage?