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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: wmax351 on April 21, 2012, 08:06:13 PM

Title: Engine Swap, 91 k75
Post by: wmax351 on April 21, 2012, 08:06:13 PM: http://www.motobrick.com/index.php/topic,2212.0.html (http://www.motobrick.com/index.php/topic,2212.0.html)

So it seems I need to do an engine swap, pending compression tests.

I have a line on a 30k mile engine, transmission, and electronics, from a 1990.

My question is: what should I replace while I am doing. I think I will do the clutch o-ring, etc, and inspect the clutch.

Is there any reason to keep my '91 transmission over the '90? When did they switch to hardened input splines?

What should I buy to have on hand while doing the job. I am hoping to be able to get it done in a week once I start. I am planning on doing it the first week of June.
Title: Re: Engine Swap, 91 k75
Post by: mystic red on April 21, 2012, 08:09:22 PM: Just out of curiosity, how many miles on that '91 Brick?
Title: Re: Engine Swap, 91 k75
Post by: frankenduck on April 21, 2012, 08:12:17 PM: (http://shop.advanceautoparts.com/wcsstore/CVWEB/staticproductimage//N2049/large/7080182_rst_00011_pri_larg.jpg)
Title: Re: Engine Swap, 91 k75
Post by: mystic red on April 21, 2012, 08:24:56 PM: Quote from: frankenduck on April 21, 2012, 08:12:17 PM
(http://shop.advanceautoparts.com/wcsstore/CVWEB/staticproductimage//N2049/large/7080182_rst_00011_pri_larg.jpg)

Our very own Paul Harvey. :loco:
Title: Re: Engine Swap, 91 k75
Post by: frankenduck on April 21, 2012, 08:32:09 PM: Hey, it'll bring back a fair amount of compression with no work. It's not as a good as a rebuild or an engine swap but it's a hell of a lot less work.
Title: Re: Engine Swap, 91 k75
Post by: Chaos on April 21, 2012, 08:34:49 PM: This would probably work better......
Title: Re: Engine Swap, 91 k75
Post by: wmax351 on April 21, 2012, 08:37:33 PM: Its got about 93k. I think its been going bad for a while, and I have just been chasing the problem. Compression was low a while ago. 155, 185, 195. I realized that it is actually reversed from what I had seafoamed. The seafoamed cylinder was still 195. I thought it was the 155 one, but realized that I was reversed. I have since seafoamed all of the cylinders.

I also checked for vacuum leaks last night. A bunch of starter fluid, and no change.

Currently, all plugs were fouled, after less than 1000 miles. The first plug was kinda glazed or something, and that is from the cylinder with 155 psi. (bear in mind that the numbers may seem high, but it is a cheap gauge. Consistency is the big issue. )
Title: Re: Engine Swap, 91 k75
Post by: wmax351 on April 21, 2012, 08:40:11 PM: Quote from: frankenduck on April 21, 2012, 08:32:09 PM
Hey, it'll bring back a fair amount of compression with no work. It's not as a good as a rebuild or an engine swap but it's a hell of a lot less work.

Haha. It would work if I was planning to dump the bike onto some unlucky craigslist chump.

But with the driveshaft (bruno's) and other stuff, there is a fair amount of value to just fixing it. I could sell it relatively easily for 2200. Getting a different bike opens up a whole bunch of unknowns, though. I was considering unloading it and getting a Guzzi, but its a hard decision.
Title: Re: Engine Swap, 91 k75
Post by: frankenduck on April 21, 2012, 08:43:30 PM: Yes, if you've got $$ into the FD then it's worth fixing. Might not be a bad idea to try the Restore stuff in between now and when you get around to fixing it though.

I believe the trannies were changed (input splines hardened) on the 90 model year but if you've got a 30K then I'd go with that.
Title: Re: Engine Swap, 91 k75
Post by: wmax351 on April 21, 2012, 08:50:33 PM: Quote from: frankenduck on April 21, 2012, 08:43:30 PM
Yes, if you've got $$ into the FD then it's worth fixing. Might not be a bad idea to try the Restore stuff in between now and when you get around to fixing it though.

I believe the trannies were changed (input splines hardened) on the 90 model year but if you've got a 30K then I'd go with that.

Yeah. I read that it changed in '89.

For now, I'll just let it burn oil and gas. Still runs pretty nice.

I get out of school on may 11th. So I can get working on it after then.
Title: Re: Engine Swap, 91 k75
Post by: wmax351 on April 21, 2012, 11:14:40 PM: Just talked to the guy with the engine/transmission. Will go pick it up late this week.

I checked the plugs. They are blackened and somewhat oiled after only 15 miles.
Title: Re: Engine Swap, 91 k75
Post by: wmax351 on April 22, 2012, 08:43:39 PM: Checked the compression before I headed to sacremento today. Was 160, 170, 175. So within 10%, on a cheapo gauge. However, the plugs seemed to have a timing issue. I checked it, and it was retarded a lot. Took a grand total of ten minutes to fix. I guess I set the timing to the wrong side of the notch when I did it last.

Doh.
Title: Re: Engine Swap, 91 k75
Post by: mystic red on April 22, 2012, 10:44:24 PM: Yeah, I kinda wondered. Takes a lot of miles to wear out a Brick. :biggrin:
Title: Re: Engine Swap, 91 k75
Post by: wmax351 on April 22, 2012, 11:55:13 PM: Quote from: mystic red on April 22, 2012, 10:44:24 PM
Yeah, I kinda wondered. Takes a lot of miles to wear out a Brick. :biggrin:

I keep asking myself, am I retarded, or is the ignition?

:laugh

Put a bit more kick into the bike, too.
Title: Re: Engine Swap, 91 k75
Post by: robleyd on April 23, 2012, 02:11:54 AM: Quote
I keep asking myself, am I retarded, or is the ignition?

Apparently you've fixed the bike and it is no longer retarded... :loco:
Title: Re: Engine Swap, 91 k75
Post by: conybeare on April 23, 2012, 03:34:54 PM: Quote from: wmax351 on April 22, 2012, 08:43:39 PM
However, the plugs seemed to have a timing issue. I checked it, and it was retarded a lot. Took a grand total of ten minutes to fix. I guess I set the timing to the wrong side of the notch when I did it last.

Did this fix the oil fouling and/or poor mpg?
Title: Re: Engine Swap, 91 k75
Post by: wmax351 on April 23, 2012, 09:10:05 PM: Quote from: conybeare on April 23, 2012, 03:34:54 PM
Quote from: wmax351 on April 22, 2012, 08:43:39 PM
However, the plugs seemed to have a timing issue. I checked it, and it was retarded a lot. Took a grand total of ten minutes to fix. I guess I set the timing to the wrong side of the notch when I did it last.

Did this fix the oil fouling and/or poor mpg?

Seems to have done the trick. 41 mpg from Mill Valley to Sacramento to Berkeley. 95% of the miles were done at <65, 90% at ~80.

Will check the plugs later. It doesn't seem to have burned much oil, if any. I refilled to the top line for easy measurement.