engine

So... This kinda feels like AA, "Hi My name is Mike and I have a problem." JK. But in all seriousness, I'm hoping a few kindhearted Journeymen XS-folk can lend me some knowledge. Experience level: Noob, like total, complete noob... Bike: 1981 Yamaha XS400HS BLUF: basically, bought diamond in...

Hi everyone! I've very recently bought an 83 XS400 Maxim, I did a compression test and have about 35 psi difference in between the two (sitting on the bike, left 130psi, right 95psi) proceeded to do a leak down test and concluded the compression is going into the crankcase. I haven't opened it...

Hey, new to the xs world and new to the forum. I just picked a 1978 xs400. It's been sitting for a long time and the motor was locked up so I started pulling it apart to see what I could find. I put some marvel in the cylinders and let it sit. Pulled the side cover and put a wrench on the crank...

Bought my first xs400 yesterday for my gf to learn to ride on and have been trying to get it run and was taking the spark plugs out and who ever worked on it last time decided that they need to be at 100ft/lbs and on the hole is stripped , I believe the best way would be to take the cylinder...

I'm fixing up an '81 engine and there is scoring on the big end of the connecting rod. Does anybody know/have a source for the big end bore diameter for the conn rod? Since the Haynes manual only has the small end bore diameter and I have not been able to find this spec elsewhere.

Hi guys/gals. I have been using all the treads religiously and have found great help from everyone’s conversations but I’m defeated with my ‘78. I bought the bike as a project for myself throughout the offseason and was able to get the bike running but only with the right cylinder. I have had...

Gday peeps thought my current xs400 chop build might tickle some of your fancies its a 70s inspired gooseneck frame hardtailed one off just started work on it this week still gotta rebuild and polish the old xs lump but planning on running a 1/2 chain driven pma alternator as the old coil and...

So my 78 xs400 has a seized engine so I went to pull off the cylinder head to manually rotate the pistons but before I could get the engine apart almost all my bolts broke in half or completely stripped. The worst part is I have no idea where to get replacements. Anyone have suggestions?

Selling everything I'm not using for a build Side Covers - $40 each Rear Turn Signals - $30 each Both Front Turn Signals w/ Headlight Mount - $70 Chain Guard - $15 Tool Box (no tools) - $15 Front and Rear Fenders - $30 each Battery Box - $25 Rear Inner Fender - $25 Seat (no tears) & Seat Pan -...

So this has been a year and a half worth of trying to figure out what is wrong with my bike. I bought this fully running about 3 years ago I think, and rode it around with no problems for about a year and a half. Here's my problem now: My idle will bounce around a bit and "searches." After...

Hi All, So I have stripped and cleaned my XS400 engine and am about to start the rebuild. I purchased a set of SS bolts for the engine off've eBay ( *Link*). This doesn't contain all the bolts for the engine assembly so I was going to measure the left overs and order individually. But then I...

I have an engine and carbs that I acquired long ago and would either like to sell the engine to someone who needs it, or buy a parts bike off someone who doesn't want it. I am not looking for a bike that is restoration worthy, but rather something that I could chop. I won't cut up a classic...

So pretty much my bike is running fine until i rev the engine, after that the rpm's seem to go crazy high and wont go back down unless I am to pull on the choke all the way, someone want to enlighten me as to what may be happening? I have a 80' XS400G if it helps Thanks,

Just got the bike a few weeks ago, was riding it yesterday and noticed as I coast to a stop the bike makes a high pitch noise. Any ideas? Thanks The bike is a Maxim 400 1983

Hey Everyone! After hijacking a few threads, I figured I'd start my own. I'm rebuilding my 1981 Yamaha XS400H (4R5 engine). It's my first bike. I'm pretty mechanically inclined but I've never worked on anything like this before. Here goes nothing… A Little Intro: Bought this guy for $600 CAD...

A friend gave me his old bike (78-79 SOHC) that had been sitting a while with a broken camshaft (timing chain came apart and crunched the socket). I've tinkered with old bikes and cars before, but never to this extent. My plan is to remove the engine completely and then just following the...

I have a problem that my bike doesn't want to go any faster than 45 maybe even 50. I have stock jets still and I'm not sure if that means much. When I screw out my fuel mixture screws nothing happens. I already cleaned my carbs. It is also sometimes difficult to start.

So, I picked up an '82 XS400RJ w/ DOHC, and as part of my tune up procedure checked the valve gap... Now I can't get the engine to mount to the bike, what started out as 2 bolts is now the entire engine... First question is do the top mounts need all 6 bolts? (2 to hold bracket on per side and...

Hey all! I've recently started an engine rebuild here and I have a Seca engine as well as a Maxim engine. My plan is to use the best bits out of both engines. I've checked part numbers and it seems that the crankcase, head, cylinder, valves, camshafts and most other internals are all matching...

Hi, I have recently bought a Yamaha XS400 1982, It's my first bike ever and I just have a very little knowledge of mechanical work. My bike heats up very fast if I go for 5 to 10 km's, a smoke starts to come out of the exhaust area. There's enough engine oil so I don't think that is the issue...