News:

Mat Oxley 1986 IOM TT


click above to read more about Mat.

Main Menu
Menu

Show posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Show posts Menu

Messages - Yamaha 179

#1
Turning Wrenches / Re: Spark plug fouling
October 26, 2021, 09:59:22 PM
All these responses are good but I'll bet AAAltered's is correct.  I have several old YMC Tech Bulletins addressing plug fouling, mainly on RDs but other bikes also, that spoke about weak coils and bad bullet connections.  They recommended removing the bullet connectors and soldering the ignition harness wires together to ensure a good
connection and replacing the RD 250/350 coils with XS 500 B coils.  (They have the same mounting studs and just bolt in place.)  Another bulletin spoke to replacing the high-tension leads even though the current leads appear to be in good shape.  Apparently, voltage could be lost through radiation or conduction as resistance through the tested leads was normal.
Lyn Garland
#2
Quote from: e30 gangsta on October 14, 2021, 11:45:59 AM
Hi fellow 2 stroke friends. I am moving from Savannah, Ga to Denver CO and I am a little worried about how the bike is going to run at that elevation. I would assume that the oxygen density is lower in Denver than in Savannah due to the elevation. Therefore the bike would be a little fat/rich for its new environment. The doubt that I have is will I have to change the jetting? We already run the carbs on the leanest clip setting on the tm34's. So all I can really change is the pilot and the main. Curious how you guys go about adjusting carbs when running them at a higher elevation.

Any tips or tricks would be greatly appreciated.

Also since I am moving to the other side of the country, Chuck will no longer be able to assist me on maintaining the bike. Besides logging miles, and top end noise is there any other way to know/measure when new pistons are required? Might be a dumb question, but I was curious if there was a was a way to measure wear or any tips/tricks.
Because If I have to visually inspect the pistons, then ill just send the jugs off to be bored, and order up a new set of pistons. Not that the bike needs a top end rebuild currently but I want to prepare myself for when that time comes.

Any solid engine builders near CO? Only 2 that I know of that are still doing work is Garret, and SCR? I'm open to other recommendations.

Thank you.
I don't have any experience with TM series carbs but I have plenty of experience in jetting VM carbs, and plenty of it in your neighborhood, Roebling Road Raceway in Pooler, GA and other race tracks east of the Mississippi.  SolCals suggestion of using the Mikuni pocket calculator is a good one and you can buy one from Sudco, International for a few bucks.  Set your Savannah (sea level) jetting then enter your Denver level jetting, fudge a size or two (for safety) and try it out.  As for piston replacement time; you should determine that by careful piston/bore comparison.  Measure the piston with a micrometer.  Measure the cylinder bore with a dial bore gauge.  The difference inn size determines when the piston(s) should be replaced.  Cast piston tolerance is tighter than forged piston tolerance.  The equipment needed to do this work is expensive and might be beyond your expertise.  Perhaps you should send the work out, but beware; many local shops can no longer do this work with any degree of accuracy because modern engines (four strokes) don't require much of it. Compare the two and the difference determines if you should replace the pistons.  It also tells you if the bore is straight or out of round/tapered.
#3
Ed Toomey. egtoome@hotmail.com
Lyn Garland
#4
Turning Wrenches / Re: Melting aluminum off cylinders
August 21, 2021, 09:53:26 AM
Muriatic acid is hazardous stuff and deserves respect.  Bad for your health and bad for your aluminum cylinders.  I don't like using it and have use a strong mixture of lye and water for years but that takes forever to work and remove the aluminum deposits.  I build a small dam of grease between the deposit/score and (say) the exhaust port where the acid may leak in.  The grease will protect the port.  I use long Q tips and have a fan blowing lightly on the area.  It is very important to have a container of baking soda on hand, not in the kitchen, to neutralize any spill.  Remember your high school chemistry.  After cleaning the cylinder wash as recommended and use a cotton ball soaked in baking soda and water mixture to ensure you have neutralized all the acid.  Then hone, oil, etc.
Lyn Garland
#5
Turning Wrenches / Re: Pro-X Piston Clearance
July 09, 2021, 11:22:24 AM
Several years ago when we were racing (air cooled) TD3s and TR3 we had trouble sourcing TD and TR pistons but could find TZ (water cooled) pistons with the same exact bore sizes.  I was concerned because there might be differences in the metal the pistons were cast from and asked Kevin Cameron about the situation.  He told me the percentage of the metal in both pistons, silicon and aluminum, and they were different but he said that I shouldn't worry; run the TZ pistons in our air cooled bikes.  He knew that we tended to run a bit on the rich side, as insurance, anyway but didn't think the mix meant anything.  We did run the TZ pistons and had an occasional seizure but it was for other reasons, mostly brain dead tuners/riders.  Of course these were OEM pistons, not aftermarket, so who knows about that.

As for determining piston clearance; I think I'd rather rely on my dial bore gage and micrometer than some idiots hearing.
Lyn Garland 
#6
Check out the coverage on facebook Concours de Competition.  Quite a few pictures; not so many two strokes but lots of good bikes.
Lyn Garland
#7
The event was very successful!  Over 80 entrants, 26 in the competition category from HD XRTT to Yamaha TD3 and the remainder in the show category.  Most from east of the Mississippi but a couple from Canada.  Beautiful weather and very interesting motorcycles.  No crashes as far as I know.  Grand Marshal wad David Aldana who rode a 1974 Suzuki500 Ron Grant special. 
Lyn Garland
#8
I've ridden at TGP since Hector was a pup.   I would have to dig out my records to see when my first laps were turned there because my memory isn't sound enough to tell you the truth, but it has to be in the '80s or '90s whenever the track was first built.  In its first layout and as I recall, first owned by a SCCA group.  Now owned by someone else.  It is a nice little track.  Easy to get to, good pit space on the asphalt (but hot), and nice pit space back in the shady trees.  Restrooms rather tacky, food wasn't available last time I was there (pre-Pandemic).  They did have race gas available but that stopped a couple of years ago (maybe more) so if you ride the Daytona take five gallons of race gas.  We always attended races there so I don't know about track days but I heard good things about the track days.  The track is interesting and fun on Yamaha twins; RDs and GP bikes.  You will enjoy it.  Have good tires!!!  The Ninga's go well there but if you are not used to racing the SV would be a bit more difficult.  Take a lot of water.
Lyn Garland
#9
Quote from: pidjones on June 25, 2021, 06:40:20 PM
Lyn, would that be 2021?

Yup.  My typo and poor proofreading...
Lyn
#10
The Barber Museum and WERA have again sponsored a Vintage Concours de Competition in conjunction with a WERA road race at the Barber Motorsports Park, Leeds, Alabama, on 3 July 2020 2021.  This is the 3rd such event and I believe all 80 spaces have been filled.  I don't remember the years or qualifications of the bikes that are invited but they are all competition machines and have been selected judged on merit.  We didn't enter last year but did in the first event and there were some really special bikes there.  Barber is a little east of Birmingham, AL, off I-20 and I think a one day spectator entry fee is $20.  A good day of racing and very nice vintage machines to boot.
Lyn Garland
#11
No they are not.  While they are similar sizes there are significant differences.  I have never attempted to replace one with the other.  I think that if you had the entire fork tube it might work but I am not sure.  The bottom of the tubes are shaped a bit differently and I don't know how that would impact the operation of the unit.  You could always try it and see but I would suggest you try both legs and not just one.
Lyn Garland
#12
Turning Wrenches / Re: wiseco pro-lite clearances
June 09, 2021, 08:06:09 AM
The Yamaha OEM pistons are manufactured and sold to bore size, e.g, a RZ/Banshee  350 first oversize piston 2GU-11635-00 measured 64.24mm by micrometer.  The Vertex Banshee 22568075 third oversize piston 64.75mm actually measured 64.70mm.  The Wiseco Suzuki RM125 2126CS 54.00mm forged piston measured 53.95mm.
The Wiseco box specifices a clearance of .0020" or .051mm. 

I believe all OEM pistons are manufactured to actual bore size and all the aftermarket pistons I have seen are sold undersize by the clearance the manufacturer recommends.  That is why I always send pistons with cylinders when I want bore jobs done and I specify the clearance I want, not necessarily what the piston manufacturer recommends.
Lyn Garland 
#13
Was it done on a cold engine with the throttle wide open?  Five or six kicks?  That is how a compression test should be done.  It might be a little weak but the rings haven't seated yet.  I would think 120psi would be more normal. 
Lyn Garland
#14
General Chatter / Re: RD hub casting flanges
June 01, 2021, 05:16:53 PM
The two TZ hubs that I have are magnesium and they have four tabs, smaller (not as tall), but they have tabs also.  I think removing them would be a mistake.
Lyn Garland
#15
General Chatter / Re: "Speed Shifting"
May 15, 2021, 12:54:52 PM
OK, I don't mean to be ugly, but this is going to come out that way; why in heaven's name would you sit at a traffic light with your transmission in gear waiting for the light to change?  Sounds like a HD rider to me!  You shouldn't be doing that with your RD and if you have trouble finding neutral at a dead stop you should do so as you coast up to the light shifting down from second gear.  Most racers learned that they can't find neutral on the start line and start trying to find it as they coast to their grid position.  The problem is exacerbated by the the rear sets they use but removing the black, rubber cushion rings in the clutch basket also worsens the clutch plate separation problem. 

A lot of racers I know do not use the clutch on the up-shift.  One very, very successful guy is like that.  I also replace gears for him every year.  Of course, you aren't as hard on them as he is, but these old bikes are not like the new ones; use the clutch.
Lyn Garland