81' XJ750RH Seca Plastic chunks in oil pan.

Yup. You read it right. The bike runs superbly. But I did have multiple minor oil leaks here and there. So I finally got the time and developed enough of a distaste for purchasing oil that I have started going through and replacing the majority of my gaskets, seals, o-rings ect. To my dismay when I drop the pan I find multiple black plastic chunks in different locations throughout the pan. I've had the valve cover off a few times to check clearances and whatnot and from that angle my cam chain guides seemed to be intact. I will be double checking them again when I remove the head this time as well. Does anyone know of anything else this may be, or have dealt with this before? I most certainly want to replace the broken part while I have it opened up.

 

It will be your starter chain plastic guide breaking up. Just replaced mine it is necessary to split the cases to change it. Apart from your cam chain guides the other guide is the only other one. They deteriorate with age and the machine develops gear selection problems when bits of the guide lock the selector drum and forks.

 

Looks like I have a winter project then. Thank you.

 

Good description and pictures here.

https://xjbikes.com/forums/threads/xj750-engine-removal-and-split-pictures.38545/

 

Thanks a million. Well done. This will be very helpful. Do you think I'm ok to wait until winter to do this? I am an everyday rider. Put on a lot of miles.

 

It will cause gear change problems and damage the oil spray nozzle behind the alternator rotor. The nozzle lubricates the starter/alternator chain. With bits of the guide in your sump you should do the work as soon as possible. Follow CDs how to l posted. He explained the process well.

 

Park her until you can do the work. The oil nozzle runs $100, and that's not the only thing that will be damaged if you keep her as a daily rider.

 

10/4. Thanks for all the info guys. I love this forum!!

 

Once you get started it is not so bad, the only problem I had was the three studs at the front of the engine which were seized and I was patient and got them sorted. The crankcases split easily, one bolt is inside the oil filter housing and four are inside the sump the rest are visible. While you are in there to replace the guide, put heat on the old bolts holding the old guide to soften the factory threadlock as they can break otherwise. Get new bolts and medium strength threadlock. Fit new starter clutch dowels and springs, mine were fine but I replaced them anyway as you don't want to split the cases should it fail at a later date.

One of Mezzmo's videos of his rebuild, gives you a snapshot of the assembly process. He has a series on his XJ conversion you can watch.

 

Awesome. Thanks again!!

 

Just curious on approximately how big the chunks were and if you had noticed any strange noises (chain rattling) or had shifting issues?

 

Dime sized or a little smaller. A bout 7-8 of them. No shifting issues and no new rattling.

 

Its likely everything will work fine until the chain stretches to the point where it will rub on the oil feed nozzle. This will be most notable at idle...

 

make sure the guy behind you at the red light knows you may only go 20 feet and loose all power

 

The chain will rub on the oil nozzle right away due to the slack not being taken up by the guide (which also acts as a chain tensioner). The chain will also hit the case, though it takes longer for it to wear into the case than through the oil nozzle.

 

Its not actually a tensioner, its just a guide. I recently fitted an OEM and guide and when new it literally makes no contact with the guide. All that chain does is rotate the alternator rotor and provide drive from the starter motor. To be a tensioner it needs to apply tension via an adjustable bolt or spring and be adjustable like the cam chain tensioner.
The wear on the nozzle is from the top side of the chain. The guide is protecting the casing, not the nozzle. Some stretch will cause enough slack to hit the oil nozzle and further stretch then damages the guide and if bad enough the casing.

One weak point on the XJ650 and XJ750 imo is the carby bowl design which creates a perfect spot for the feed to the choke to block.
Once this happens starting becomes much harder and this is what I think results in chain stretch.

 

The top side of the chain can also hit the case when worn. I head it on mine and I have a video posted on here showing the stretch in the chain. My guide had not broken up but I replaced it anyway and the oil nozzle was fine.

 

Agree Franz. The only positive I guess is that there is usually a rattle warning it’s on it’s way out. It’s unfortunate it’s not a simple job to replace though...

 

Yes Mezzmo mine rattled a bit, and I don't like that but it's sorted now.

 

I’ve done the job to my own bike. I’m not wrong. The guide does apply a slight amount of tension. If your HY-VO chain is worn then it won’t do that. HY-VO chains don’t stretch. Even single-pin chains don’t stretch; the pins and rollers wear.

 

I'll just put these here.

 

Nice bike.

 

Thanks.

 

Nice indeed. She does need some sort of trim plate between the tank and the seat to fill in the gap from the stock sidepanels though. The peg hole and notch draws the eye in a not so flattering way.

 

What make are your panniers?

 

Agreed.....I've kind been looking for a piece of some sort of rubber trim to cut and put there, but haven't seen anything quite right. Good news is......When I'm riding it my leg covers it up. lol

 

Saddleman

 

A 3-D printed peice would fit in there nicely. Is there a makerspace in your area?

 

Don't believe so. Never heard of it.

 

that would be a nightmare to 3D print

 

Nah. Once the model is built in CAD it's pretty easy. Compound curves are not a problem with supports. It'd be even be smooth and strong right off of the build plate using non-planar slicing (once I figure out how to do that myself).

 

A Makerspace is like the rental garages that used to be around in the 70's. Anyone who wants to build stuff, but doesn't have a home shop, can rent time on their machines. A lot of makerspaces have members who will do work for others. Most of them are in mid-size to large cities.

 

you have a printer, we have to talk.
if was modeled in CAD i'd put it on the cnc mill and do it in aluminum.
but really i think a piece of 1X pine would be the fastest

 

I'm just starting to play around and learn with mine. I have an Ender 3, and most of what I've been printing has been minis for a game, but I have done quite a bit of talking with by engineer brother about 3d prints. The company he works for uses them for some of the processes in their production of sintered parts, and the only significant difference between my printer and theirs is the size. They even use the same software.

I'm currently printing a setup to make it easier to balance my wheels when I change tires. If the material holds up like it's supposed to I'll move on to printing more functional devices. If I wanted a part like that in metal (lacking a CNC mill) I'd print it in SLA and cast it in aluminum. That is if I hadn't needed to leave my casting stuff behind when I moved.

 

Yea I may have to try that and see how it looks. I'm a good fabricator/welder but I'm no machinist.