Introduction and general questions - Midnight Maxim 750

Wanted to introduce myself and my newest project. I started off riding with my dads 1978 Yamaha DT125 that I’ve grown up with it sitting in garage, bought a new battery carb to get it running and not only started my motorcycle career, but fell in love with vintage bikes. After outgrowing that I purchased a 1983 Midnight Maxim 750. Absolutely love this thing. Bought it right under 30k miles, PO I bought it from put a few hundred miles on it and then had it sitting for a while. Has a number of small issues which I’ll get into shortly. I’m diving into custom bikes more and more and I’m wondering how much of a time piece this is and if it is just destructive to modify this “special edition” bike.

current issues :
1. High Idle
noticed some surface rust in the tank so I’m assuming the carbs are a little gunked up. It runs and drives great but usually idles pretty high, around 3k RPM along with some popping (and under heavy higher rpm deceleration). There is also a 4-1 exhaust (that has a pinhole leak with different bolts on one cylinder) that I’m also assuming never got rejjeted for. I’ve ran some B12 through it a few times and helped popping while riding a good bit but still will. Sometimes I can trick it into idling lower with clutch in/out but it will slowly slowly drop to a lower RPM enough to die, not the worst thing to deal with while riding, but still an issue. One of the intake boots was old and needed replaced so I grabbed one which helped the idle but BARELY.

2. Front Brake caliper seized? Seems to be leaking fluid onto the rotor, good pads brakes are OK but not the greatest. Replacement caliper or rebuild kits?

3. Speedometer needle broke.
Probably will just save my pennies and buy an aftermarket setup, there is a section in my book of rebuilding them as it vibrates a little bit so that’s an option too.

4. Little things
Choke cable has a little kink, not sure if I should be worried seems to do its job. Rear shocks seem a little worn, what are good options for replacement? buddy of mine said he saw some black smoke once from me so I’m guessing piston rings are worn? Thing runs like a champ and bangs through the gears very well.

I’m stuck between restoring it perfectly and putting it in storage or making a sick custom bike (cafe, brat, ect.). Regardless of that, engine wise what is my best bet for bringing all life back into it? I would assume full carb rebuild/jet/sync (pods?)? Any kits for engine rebuild gasket, seals, rings? Sorry for long generalized post. Im sure I’ll (have to) make separate posts once I really start diving into the crazy machine.

 

Love the bike man, looks amazing! That color scheme isn’t something I would’ve thought of but it just works for me lol the high idle sounds like vacuum leaks maybe around carb boots but throttle shaft seals and full rebuilds would be best to start. Leaking front caliper is probably in need of some love and just going over all that stuff for peace of mind isn’t a bad idea. Brake lines and rear shoes if that’s a thing would be nice to have done as well. Could be carbs are running rich/just out of ideal spec in sync and/or jetting or settings for the occasional black smoke puff, rings are going to show more during a compression test. Valve clearances should be checked before you’re super comfortable taking her for rides but being able to ride in between doing chapters of the project really help with motivation I know. I personally would not be worried about the choke cable link unless you can see the individual strands breaking. That cable does not have a lot of continuous stress placed on it compared to the throttle and clutch cables. Also the midnight specials are kinda a nice special package I believe.

 

And from another post, Dave in Ireland said he had seen a post where an Xj750 was purchased with gs750 pipes on it. So personally don’t know about your exhaust options but with a little massaging who knows what you could fit if you don’t feel like repairing the current ones.

 

I'd put some flatter bars on it and fix the issues one by one. Some stuff you should do before riding it further - brakes and valve clearances would be top of my list.