Problems with 1981 Seca xj750

Exactly. I think I can see the dot on the exhaust aligned with the cap but I can't see the dot on the intake. The lobes appear to be positioned correctly. If so the T on the timing plate is not aligned with the fixed pointer. I can't tell if piston 1 is truly at TDC. I was waiting to see what you guys see.

@All the members who replied reguarding the supertrap... whomp there it is!

Gary H.

 

That's great news! If you have any doubt about timing post up a video and let the pros (not me) take a listen.

 

Great, Glad you found the problem. I would consider getting rid of the supertrapp......... Swap the parts back one at a time, just in case.

 

I like the look of that one. All stainless and it doesn't look like it doesn't belong on his bike. I'd keep it and get jetting and shimming help (if necessary) from the members here to dial it in.

Gary H.

 

I would suggest that if the does he send it to me......
The Supertrapp was one of the better improvments that could be made to the Seca back in the day. Unlike the stock exhausts however, it requires some occasional maintainance.

@Rocs. It probably has the correct jetting for the pipe already (worth checking on though). Those were not cheap, and would have likely been put on at a shop when the bike was still fairly new.

 

Agreed. It's a nice one for sure.

Gary H.

 

I would also suggest double checking the timing. Don't rely on the timing mark at the ignition. Use a pencil or a dial indicator down the #1 spark plug hole to find TDC.

 

All good points.... The Supertrapp I have on my dual sport gets the disks removed and cleaned every season. I have never repacked it, however. With that much carbon in the exhaust, I would suspect the bike to be running rich. As I recall, the fuel mileage was very low at the beginning of the trip.

 

For members that may not know your compression gauge and vacuum gauge(s) can be combined to quickly find TDC. You'll need a short piece of hose with the proper diameter to do it and a hose adapter. Remove the shrader valve from the compression gauge, connect the two then use the vacuum gauge to find TDC (it works good on cars). The pencil or straw in the hole is much easier and quicker. Just thought I'd share this since k-moe mentioned using a dial indicator.

Gary H.

 

so 8 plates are packed with carbon and that's all that fell out when the cap came off, ok. and that's a picture of the cam marks at tdc, ok. now you're running a open exhaust and the bike runs good.
great, glad you fixed it

 

IF that Supertrapp comes off, put it up for sale here... you may see a biding war!

 

Ha, what a troll you are Polock. I'm pretty sure he won't run it with the open exhaust and if he does we'll all get in line to slap him with a large trout. Don't sell your Supertrapp, whatever you do.

 

Un Uh.....I already called dibs lol


What we know: There was an exhaust restriction, and the cams look like they are out of time, but obvously not out of time enough to keep it from running. There is still work to be done in order to ensure that the bike stays running with the restrictor plates back in.

 

Dibs are yours, I'll admit. But I got a big stack of government cash burning a hole in my bank account!

 

You guys are too funny about the bidding war on the SuperTrapp... Just to clear things up I'm planning on keeping it on the bike now that I understand it. I agree that there is still tuning work to be done on the bike but I am super excited that it's at least running now.

 

then I am your fire department - send those Loonies and Toonies my way!

 

Hey guys - I just wanted to follow up and tell y'all that I just took this bike on a 2400 mile trip from my home in Southern California up through Las Vegas where the temps were 110 degrees, on up Idaho to visit family for a few days then up to Yellowstone Park at an elevation of over 8500 feet, on to Jackson Hole, Wyoming then back to Utah to the Bonneville Salt Flats where I took the bike up to about 100 MPH on the slat flats, ran into a hail storm and flash flood in Nevada, then back to California - 5 days of riding time. The bike worked great!!!
I am very happy that you all helped me get it back on the road. I feel redeemed from the u-haul trip I started in New Mexico back in May.
I think it was Rooster53 who first suggested I might have a restricted exhaust. THANK YOU VERY MUCH!!!

RusteeGold - AKA Steve Gold

 

Awesome trip. Wash the bike a dozen times or so. That salt gets everywhere.

 

Glad its running well and glad you had a nice trip, Steve.

 

That's just.. awesome.