Plugs fouling, top end rebuild?

[5twins]

I would get 45 and 47.5 pilots. If you look at the chart above, you'll see that Yamaha reduced the pilot jet size to 42.5 after a couple years. There were no other jetting changes made. That would seem to indicate that Yamaha found the 45 pilots to be a bit too rich for the bike. That means they might be just right for your bike with minor mods. Pilots are usually increased one or two sizes on these bikes with minor mods, mains about the same. Remember though, yours is an early non-E.P.A. mandated set so will be richer to begin with. You shouldn't need jet size increases as much as some of the later carb sets would.

As far as straight pipes go, they're not the best choice for any engine. You lose low end and midrange power with them. They can also be hard to tune for. A muffler of some sort is best, both for performance and ease of tuning. Your early type mufflers were supposed to be the best sounding and performing stock mufflers ever put on the 650.

 

[weekendrider]

Nice looking bike. Big like for the seat. For the exhaust slash cuts ending just shy of the rear axle (imo) kinda balances the front drum brake.

 

[Tecrekka]

Thanks again 5twins, I'll try out the jets you suggested and see what happens. I've read that everyone is so happy with the particular pipes I've got on the bike (stock), but I'm just not crazy about the "Big fat cigar" styling. With the solo seat on this bike, it seems to drag out the back lines and make it look flat. I am planning on probably getting another fender and cutting it to about where the actual frame is (rear seat support?), and removing the bar the taillight/fender is currently mounted on. When I do this the stock pipes will be longer than the termination of the fender. Who knows, maybe it will look right. Whatever I do decide on putting on has to extend to at least where the rear peg/exhaust mount reaches, as I don't want to cut that off but I also don't want that just floating out here in limbo.

Thanks weekendrider, I agree, I do like the slashcuts as well. I realize the original pipes surely perform well and they DO sound good, you can tell it's not your average crotch rocket or Harley coming down the road, but man, we took those pipes off yesterday and cranked it, it was music to my ears! lol I don't want to sacrifice performance simply for loud pipes (save lives!) so hopefully I can find a happy medium.

 

[5twins]

Mike's has a pretty good selection of shorter mufflers. Unfortunately, a simple fact about mufflers is that the longer and bigger they are, the better they work. The traditional 12" shorty muffler, which Mike's appears to have a version of (#07-0010), doesn't do shit and is basically just an extension on your straight pipe. I would recommend something like this or this .....

http://www.mikesxs.net/product/07-0062.html

http://www.mikesxs.net/product/07-0114.html

They also carry a slash cut muffler if that's your cup of tea. Back in the mid '70s, BMW had a factory endurance road racing team. They found the best exhaust for their twin to be a 2 into 2 with long gently tapered megaphones. I wish the Chinese would start cloning the Conti muffler. That had to be about the nicest looking and sounding muffler ever put on a twin.

 

[Tecrekka]

Well I'm feeling very optimistic, my plan is to get the new jets on Monday and get the carbs straight, change the oil and maybe change the sprockets to an 18/30, check/adjust cam chain, check/lube/adjust chain, and drive it to NY...840 miles. I've got to go anyway, and it would be so nice to take the bike. I know it would be somewhat brutal, but unbearable? I've read that if you are tuned well the vibration isn't as bad and that gearing really helps. Thanks in advance for input.

 

[gggGary]

The vibration is no big deal. I ran up 250 miles pretty much in one sit last week on my stone stock 79 no vibration issues. And I am old and crippled. (recently got tossed off a horse) The hard part on a trip to new york now will be staying warm!

 

[5twins]

No kidding, I'm sitting here in New York this morning with the furnace on.

 

[Tecrekka]

That's the truth! I've been keeping an eye on the weather in Albany and at the moment it's not too bad, though. Daytime highs are in the mid 60's, and nighttime is low to mid 50's. If I do it I would plan on doing most, if not all of it during the day, just in case I need to do some roadside modifications, haha. Also, I'd plan on getting out of there asap on Sunday is it's supposed to start to rain and continue through Monday. As per 5Twins suggestion, I put the factory pipes back on, at least for now. When my new jets arrive tomorrow this will at the very least give me a good solid base to tune on.
Something dawned on me yesterday while tinkering with it, the guy that had worked on it before never replaced the piece that links the chokes on the carbs, so, I was only choking the left carb. Should be a pretty easy part to fabricate if I can't find one locally. If I've learned anything it's that the dude that was working on this for me will never see this bike again!

 

[5twins]

Well, you might want to show it to him one more time just so he can see how well YOU got it running - no thanks to him.

 

[gggGary]

Yeah the "local carb expert" tale of woe is oft repeated.
Post up how the trip goes?

Wood stove's been going here for three days now.
Got a pile of warm clothes on the floor ready for today's 150 miles to the Slimy Crud Run.

 

[Tecrekka]

Well, you might want to show it to him one more time just so he can see how well YOU got it running - no thanks to him.

True, I have considered that. Ride in the with absolute incorrect jets in hand and see if he even knows what they are. Ha

Yeah the "local carb expert" tale of woe is oft repeated.
Post up how the trip goes?

Sure thing, I'm looking into wiring a voltmeter and accessory power at this very moment. That way I can update with photos from the road. If I do it I'll probably start another thread for the trip and update here as far as performance or any other mods I need to make along the way. Hopefully I'm not posting to this thread from the side of the road somewhere outside of NYC saying "what the hell happened??" haha.
Luckily I've got some friends just this side of DC area, about 2/3 of the way, that I can stop and rest at.

 

[weekendrider]

Convinence stores/gas stations/most office buildings generally have outside electrical outlets.
Waiteress's can find you one in a restaurant. Ask for a booth or table with one available.
Even a seasoned butt will welcome an extra 20 minutes to stretch after 400 miles.

 

[Tecrekka]

This is true! My phone does charge rather fast, but I would still be nice to have mobile power. I'm not going to be too concerned with it, but it is a possibility I am looking into.

 

[weekendrider]

A couple other travel tips.
Newspapers make cheap chest padding if the wind is getting through.
Rubber bands for your sleeves. And yes I've used both in the past before cell phones and travel stops every 20 miles.

 

[5twins]

As far as gearing goes, I wouldn't recommend the 18T front. It can introduce clearance issues, sometimes requiring the removal of the shift shaft guard, and if you let the chain get too loose, it can start gnawing away at the clutch pushrod and/or shift shaft. Just reduce the rear size some.

 

[Tecrekka]

A couple other travel tips.
Newspapers make cheap chest padding if the wind is getting through.
Rubber bands for your sleeves. And yes I've used both in the past before cell phones and travel stops every 20 miles.

Ahh, I've used rubber bands but didn't think about newspapers, thanks!

As far as gearing goes, I wouldn't recommend the 18T front. It can introduce clearance issues, sometimes requiring the removal of the shift shaft guard, and if you let the chain get too loose, it can start gnawing away at the clutch pushrod and/or shift shaft. Just reduce the rear size some.

That completely makes sense. That was a frequently occurring formula that I was seeing on discussions on the matter but I would really rather not mess with the front sprocket if I can avoid it, anyway. Good to know that it isn't a good idea in general.


[Today]
Proper mains don't arrive until tomorrow but I had to get it out today and see how it would do on more than a block run. It was a bit rough to start but it was a bit cold today and then again I can only choke one carb and manually hold the R carb once it got started. It seemed that when choked it would idle quite nicely around 9-1100 without much issue. If I tried to hit the throttle early on it would bog down, which I expected when cold. After a few minutes it would respond fairly well when I coaxed the throttle. When I let out the clutch it seemed I really had to wind it out to keep it from stalling though, and it was a bit jumpy taking off. Once I was above 8-10mph it took off just fine, and accelerated smoothly. Once up to speed, it performed fine. I drove it about 10 miles and no problems, until I idled down/stopped at a light. If I came to a complete stop and let it idle down, it would usually stall, and be a bit of trouble to get going again. It seemed that even when warmed up it was still starting like it was cold (I would attribute this to the small pilots?). On the trip back I noticed that at speed (40-45mph) I could still feel the occasional stutter. The new jets come tomorrow and I can only assume that they will help with some of this but I just wanted to update while it was still fresh in my head. Thanks again everyone for your input.

 

[Tecrekka]

Got the new jets installed, I've been doing homework like crazy the last few hours or I would have already had it done! The ones I got are 45's, as opposed to the 40's that were in there. I've put them in and turned the mix screw out 1 turn. Here goes nothing!

(New jet on right)

 

[Tecrekka]

No dice. If there is any improvement it is imperceptible. Anything below 3k is shit, popping, bogging and eventually stalling. Anything above 3k is just fine.I started out at 1 turn out and eventually got to 2, with no noticeable difference.

 

[Tecrekka]

Okay I think I'm on to something. Pictured are the new spark plugs I put in today, left and right, as well as the left carburetor in my hand in a position where I feel a puff. The right cylinder seems to be performing correctly as evidenced by the sound coming from the exhaust. I noticed that the right side seems to be working more than the left. Judging by the plugs but I just pulled out this seems to be correct. Although there appears to be no gap in the top of the left carburetor, it certainly seems that this could be a spot where there is some type of leak. My inclination now is to pull the carbs in take the top off of the left one.

 

[Tecrekka]

( this was after only idleing for maybe a minute or 2)