XJ700x XJ750 Mutt Chopper: Marie

Hello all,

I have returned to the forums after a long wait and many miles to gain knowledge and clarity about my old project bike named Marie.

She began her life in 1985 as a XJ700x, traveling far and wide for approximately 45,000 miles. You can find some older posts of her in her past life.

I fixed plenty of old sins, where prior owners took her 25k without doing a valve adjustment, running 15w30 through her, and generally abusing the p*ss out of her. I received her for a song in 2011 and thus our life together began. As an overly enthusiastic kid, I began rebuilding her and while fixing and lightly modifying her, I made plenty of my own mistakes (See prior posts about the erupted head and errantly taking a dremel to her poor cv carbs. All told, after fixing my own mistakes along with the past 'rednecking' of electronics especially, we had some good times together, going from my home in Cleveland to Tennessee and New Jersey, generally having a good time.

Then came the summer of 2013 (I think). I was riding down a local interstate (I-90 for any Cleveland'ers) around a bend between two municipalities, when I hit some gravel where I lost the bike going around 70 mph. I burned through my Shoei helmet, a 200 dollar jacket, gloves, shin guards, and some layers of skin off my rear. Unfortunately, the most heartbreaking loss was the engine to my poor Marie. The case had dragged along the ground and during various Michael Bay-esque unmanned maneuvers, the engine grenade'ed. Unfortunately, at this point all of my best work into this engine is for naught, and I seriously considered just cutting my losses and letting the junker take her to that great highway in the sky.

Luckily, I did not. After a quick injury check, mostly just a bruised ego and the aforementioned road-rashed buttocks, I called a friend with a pickup and we hauled her back home. With the losses, what I was left with was a solid frame, and a nuked engine. My rims and forks somehow were solid, and thus I began to build anew. In the mean time, I built a Cafe Racer out of my Uncle's first bike that he gave me for $100 a 1975 Yamaha XS500 (named Brittney). I have ridden her faithfully for the last few years, but every time I pulled into the garage or washed the bike, I found myself daydreaming about my old wreck, Marie. So by the end of the summer and into the winter, I began planning and building what I wanted to do with her.

Since the engine was wrecked, I began looking around for a replacement waterhead motor. Those that did NOT have a rod thrown had been going for 650 or so, and could not guarantee compression or when it last ran. So I did some research and measuring off of a friend's XJ750. I found a 1982(?) XJ750 motor on fleabay at a boneyard about an hour away from me for around 250. He had it hooked to a battery and a starter motor, and happily got a cold compression reading on the engine, and I purchased it.

Over the course of 2013-2016, I began building, rebuilding, and rebuilding a 70's throwback true-hard-tailed chopper. I left only the neck, the cradle of the frame to the engine mount, and the forks. After long hours in the shop, I finally had welded the frame together and began rewiring her. I used a 2.5in solo speedo, no tach, TCBros Choppers 3/4 rear axle plates, 'clubman-style' bar end mirrors, a Honda VT600CD rear axle, a springer seat from india, enough hardened bolts from my local hardware store to be on a first name basis with everyone there, some straight-pipe baffles, two VM-34s running to a "Orange-n-Black style intake manifold using some square pipe, Dyna DC 1-1 coils, a round taillight similar to those model T tails chopper builders are so fond of, and a cool spiderweb gusset (that last one was essential). Other than that, I used more DOM tubing than I'd like to admit (measure once, cut 4x and throw the mistakes like boomerangs), spool upon spool of welding wire, and almost a full tank off my oxy-acetylene rig.

After having setback after setback due to money, time, moving, marriage etc. I got the frame finished. She sat all this summer until yesterday due to a dumb wiring mistake (I forgot to run the red/white wire that goes from CDI to coil over to a power source, disallowing the bike to run). Well yesterday, I realized my error and got her back up and running.

This brings me to my latest set of questions. I had a condition where if i would start the bike without the enrichment circuit, it would idle extremely high (6k-ish best guess without a tach) sporadically dying, and if i ran the enrichment circuit, it would either die, or idle lower if I kept the throttle feathered. I realized I did NOT block off my YICS like I should have (Forgot I had it, as the last XJ I had was my initial 'x'), so I need to do some testing.

Last night I yanked the carbs and ultrasonic'ed them, rinsing and blowing through all ports and jets after they were sparkling clean. Can anyone else help me through any other steps to try if blocking the ports and the cleaning did not fix it?

ALSO: I noted on my ride, the shifting seems to be reversed. Where I would expect 5th to be, I clearly am in 1st, with a very clear neutral between what I would expect 4 and 5 to be. I rode it with the above engine issues last night and got through 1-4 (or 5-2 if it were a normal bike shift pattern,) Has anyone heard of this happening? When I first got the motor, it had a ball and socket linkage on it, but with my mid-control direct-off-gearbox shifter, the shifting seems opposite what I would expect. Is that possible that it came out of the factory like this? I wouldn't mind reversing it, if I knew how it was accomplished in the first place.

(I promise I will get some more pictures up to illustrate my story, I am at work today, and am unable to walk out and take pictures of her as she is safely in my garage presently.

 

1. The YICS ports do not need to be blocked.

2. You likely have a vacum leak. Spray carb cleaner around methodicaly at idle to find it. I'll wager that it's either cracked intake boots or throttle shaft seals.

3. You have the wrong shift lever. The 750 airhead used a linkage system (notice the "extra" hole in the shift cover).

4. Please keep everything for this bike in one thread, so we all can keep track of what has and has not been done. Problems often hae multiple causes, and if the problems get spread out over several threads it becomes easier to miss something

5.
IN THE CHURCH OF CLEAN

TECH TOPIC: The Real Costs of Maintenance

The Information Overload Hour

 

Hey K-Moe,
1. YICS ports need blocked due to Non stock carbs, as stated above, referencing Orange-N-Black's project,
2. I will check the vacuum leak situation, no throttle shaft seal due to non-stock carbs, but the problem I have with that logic is, why would that bog down the engine when extra gas is added via the enrichment circuit? If extra air was getting in via boots, that would lean the mixture, thus adding fuel with the enrich would have it idle higher no?
3. Could you provide pics of the shifter lever you speak of? Is that to say a direct off gear box shifter is expected to be reversed?
4. Bike is completely different than every (3+ year old) threads with absolutely zero commonality. And I have never done a project thread.
5. Not my first rodeo, been a member since 2011, non standard carbs, and I've read them. Thanks though.


(Edit: Ill be D*mned, I did start a project thread before. any way to delete an old thread?)

 

How much research went into this project?
~Ghost

 

Well, I did a fair amount into the car/airbox situation and had a pro fabricator friend help me with the structural welds/measurements/bends. I am certified on mig and tig and did all the finer welding. My research on the motor itself honestly was minimal, I rebuilt a xj550 and a x700x before hence my confusion on the shift pattern. This is my second full frame build, did a cb750 a few years back.

Why do you ask?

As a follow up, I am now idling well with good color tune readings, no vac leaks, and now i am rich at throttle. I am looking into rejet to lean out my mid range. Looks like the carb clean fixed the idle issue.

 

you asked
3. Could you provide pics of the shifter lever you speak of? Is that to say a direct off gear box shifter is expected to be reversed?

yes it will be reversed linkage set up pulls from 12:00 position

link to shifter lever on 82 XJ750

http://www.yamahapartsnation.com/oemparts/a/yam/500421e1f8700209bc787428/shift-shaft

 

Many thanks! I'm not terribly worried, gp shifting is just a little mind over matter, and it's just forcing me to chase down the parts forbthe next project here: a hand shift foot clutch. I just wish I could afford those little micro bar panel switches to eliminate mine.