crono
L plate rider.
Posts: 12
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Post by crono on Sept 9, 2019 19:56:04 GMT 1
Hi all,
new to this board and relatively new to the RD, YPVS. Fortunately not new to 2 strokes. I just restored a 31K and got it back on the road after tests. It has been used as a track bike since over 20 years. But it's running fine. Still some issues but that will be solved. I have 2 other 31k's to restore and a spare engine and barrels just in case . As my commuter has a dead battery and it still hasn't arrived I am using the 31k as commuting bike, not ideal in busy traffic but it works.
This is my 1st. Yamaha RD 350 LC ypvs.
Everything OK, but the rear end, it's very nervous and extremely sensible for joints in the road. I am running Bridgestones Battlax, which were the same used for classic racing.
I find the bike rather unstable, it comes clearly from the rear. Joints in the road, a bit of side wind, etc. is enough no start a kind of shimmy (not a tank slapper as my old Kawa 500 Mach1 tripl), its not violent, just weaving/floating. Putting some more weight to the back seems to help a bit, same as getting my head and body down on the tank. ( looks a bit strange to see an old fart as me flat out on the highway). This is worse at a constant speed. Does not occur accelerating and is worse around 140 km/h. Over 160 its better but then of course you have to slow down again. Also I have to avoid radars and speed tickets! I think its the rear. Linkage is in good condition, new nylon bushes, rear swingarm spindle is new and with new needle bearrings, no play. New rear wheel bearrings too. Any suggestion? Someone told me to put an FZ rear swingarm? As it is my first 31K not sure if this is normal. Any cures for this?
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Post by hoist1 on Sept 9, 2019 20:36:15 GMT 1
Hi, new myself. If you are happy with the rear shocks and tyre pressure is the tyre evenly on the rim? Don’t suppose an unbalanced wheel would be it but I would be tempted to eliminate anything at that end.
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Post by midlifecrisisrd on Sept 9, 2019 20:52:57 GMT 1
Hi
You say 31k but what year
There are 3 models of 31k. The lc2 with the bikini fairing can be known to weave at speed
First thing I'd look at is rear shock as if the damping has gone it will affect it badly
I'd also check the wheel alignment if it's been on a track
Steve
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Post by hoist1 on Sept 9, 2019 21:12:49 GMT 1
Hi, new myself. If you are happy with the rear shocks and tyre pressure is the tyre evenly on the rim? Don’t suppose an unbalanced wheel would be it but I would be tempted to eliminate anything at that end. Of course I meant shock singular, think I have rd400s on the brain a bit.
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Post by arrow on Sept 9, 2019 21:37:09 GMT 1
Welcome to the forum. Hope you get the issue sorted.
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Post by rfloyd350 on Sept 10, 2019 2:09:21 GMT 1
hi and welcome. new to the site as well and had a new 31k back in 84, bike was always good till i put a wider rear race tyre on then bike would weave at speed. maybe worth checking whats been fitted since its been on the track. cheers
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Post by dusty350 on Sept 10, 2019 6:56:31 GMT 1
Hi Welcome to the forum Dusty
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Post by rigga on Sept 10, 2019 11:24:43 GMT 1
Welcome Again worn shock or swing arm bush's would be my guess.
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Post by wallcraft on Sept 10, 2019 13:31:28 GMT 1
Welcome in mate. I had a weave problem on my LC, not like a tank slapper but unstable and sensitive to raod joints, turns out I had a 120 profile on the rear so changed to the correct 110 and it transform it, no weave just stable.
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Post by Dangerous on Sept 10, 2019 15:38:51 GMT 1
Welcome to the best forum around👍
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Post by Mr Kipling on Sept 10, 2019 16:46:03 GMT 1
hi and warm welcome to the fold , enjoy the site.....
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Post by Yogi on Sept 10, 2019 17:06:41 GMT 1
Welcome aboard mate 👍
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Post by shaunthe2nd on Sept 10, 2019 17:11:17 GMT 1
Welcome to the cool club!
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crono
L plate rider.
Posts: 12
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Post by crono on Sept 11, 2019 11:50:05 GMT 1
Thanks everyone for their inputs. The rear tyre is a 110/90, standard woudl be 110/80.
The rear shock is that of an R6. I think this might be the cause. I have another WP shock which is specific for the RD but needs to be repaired. That why I had the R6 place, this shock was new but surprsingly "dead". Its a 31k 1985, with standard mufflers but I have also some Arrows which respond much better but are a bit noisy for road and I ahd to take tehm of for the technical tests here which are very severe. To give an example they reected passing first time because of the 110/90 instead o 110/80. I had an old wheel with a completely dried out 130/70 which I "restored" with black shoe cream to make it look better and passed. (BTW with the 130/70 it was similarly weaving). Frame is straight, it had no severe crashes. Frame ha still original paint and was never repaired. I willchange shock ad see what happens
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new member
Sept 11, 2019 14:35:36 GMT 1
via mobile
Post by dusty350 on Sept 11, 2019 14:35:36 GMT 1
The Yss range of shocks are excellent value for money, rebuildable, adjustable and have a 2 year guarantee. Hard to beat for value. By the time you get an old shock repaired/ rebuilt, there may not be a lot of difference cost wise.
Dusty😉
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Post by Tobyjugs on Sept 11, 2019 17:04:14 GMT 1
Welcome to the forum
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new member
Sept 11, 2019 17:39:48 GMT 1
via mobile
Post by wallcraft on Sept 11, 2019 17:39:48 GMT 1
Welcome in mate. I had a weave problem on my LC, not like a tank slapper but unstable and sensitive to raod joints, turns out I had a 120 profile on the rear so changed to the correct 110 and it transform it, no weave just stable. Sorry I’ve given you duff info, the profile was a 90 which gave me weave so changed to the stock 80 profile and lost the weave 👍 Mark.
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crono
L plate rider.
Posts: 12
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Post by crono on Dec 16, 2019 19:51:27 GMT 1
well, just wanted to let you know whay I did to get the bike handling better.
I started to rebuilt the entire rear swing arm bearings, new axle, needle bearings and seals. Bushes upper and lower linkage, and dog bones are now all new. Rear wheel bearings, completely rebuilt rear shock. Absolutely no play in any of the parts, swing arm, linkage whatsoever. It has improved a lot. treid with a variation of tryre pressures. Best 2,2 front 2,4 rear. It's still very sensible to joint in the tarmac in the rear and I know now that it is definitively the rear tyre. Bridgestone BT45's.
I never liked Bridgestone on any of my bikes and I do not like these either.
When I raced in the 70's I loved the Dunlop KR series and did not like at all the Michelin PZ2 of that era.
Any suggestions NON bridgestones.
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Post by arrow on Dec 16, 2019 20:07:25 GMT 1
I had Continental Conti go's on my LC and they were great.
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Post by hoist1 on Dec 17, 2019 0:10:01 GMT 1
Are they new tyres or were they what came with the bike? Had bt 45s on a cb500 twin and they performed really well, take it your issue is when upright?
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Post by veg on Dec 17, 2019 0:29:39 GMT 1
Avon roadriders same as the old am22/23s sticky compounds etc get my votes and used by lots of classic racers
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Post by mak595 on Dec 17, 2019 15:28:59 GMT 1
Got Roadriders on both my ypvs but one has only done 5 miles since completed and the other is waiting for me to rebuild the motor so cant really comment on the tyres except their black and round
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Post by mouse on Dec 17, 2019 15:48:18 GMT 1
Hi
Try this
I have a 31k LC2 (bikini fairing), when i got mine it was totally standard and it weaved like a bast**d at anything over 80mph. Then i took the fairing off and tried it...no weave!
I have since hybridised the bike with an RGV front end and refitted the fairing, still no weave!
Just a thought
Mouse
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Post by stusco on Dec 17, 2019 17:04:36 GMT 1
My lc2 back in the day used to wobble until I smashed the fairing and removed it even with a steering damper
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Post by shell2tx on Dec 18, 2019 11:00:18 GMT 1
I had a wrangler lc2 for a short time in the 80s it would do 2 wheel slides around slow corners it had dunlop arrowmaxes on it i think they were made from recycled banana skins or summit the worst tyres ever thought up... swapped it for a CR500 ha ha
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