Messages

Lean blistering plug dangerous . Plug may be too hot also for conditions

Rich,
He got some bad info on break in premix ratio and was running 20:1 and of course your right it will run leaner with the jets he has in them now.
Now that he has some break in time on it... he'll get it on a fresh mix at 40:1 and a gearing change will start to get him on the right track.
Chuck

Has the engine been rebuilt with a new crank rebuild?
When main bearings get old and loose they let the crank seals leak at speed...
Chuck

Chuck:
Used your marninate on steaks we had for Father's Day.  Rave Reviews!  Thanx!!!
Lyn

Good to hear you tried it!
The bonus is you don't need any steak sauce!
C 

New Spec2 F1-pipes are better on the bottom than the older version Spec2's you have.
Gearing change is a must if your trying to run stock gearing as the Daytona 2V0 cylinders have some very low port emission porting and ran higher gearing than the STD 1A1 RD400's.
Daytona came stock with 17/37 and the 1A1 were 17/38.
First thing would be a 16T front, then a 39T-40T in the rear all depending on how much highway riding you want to do?
My overported Yellow Screamer still can cruise 70-75 mph even with 16/42 gearing.
I've only stayed with new VM28's, never tried VM26's on a RD?
If running a 90 sized rear tire...it will want the lower gearing too.
Chuck

Good job, it did look like the gray case sealer and not silicone sealer...
Chuck

Lacquer thinner and a s.s. bristle brush work well.
Cant really tell in the pic, looks to me like Yamabond 4 (hondabond, motoseal, 1204 threebond, etc.)
C

Scott,
These RD's just need some special guidance to be reliable on pump gas, this is not the 70's and 80's when we could get away with a lot of stuff we did to them.
Just need to go through the entire setup.
Depending on how big the bore is, stock heads are good to 65mm. I would cut them for reduced cc's after 65.25. this is on stock or mild porting setups.

One big role is to have a rebuilt crank or at least inspected, trued maybe some new outer main bearing with new seals at minimum.
That's your foundation to start, then fresh bores and pistons, then setup proper intake system and carbs to suit.
I like to drop the front sprocket a tooth for RD with chambers to lesson the detonation load on the engine with todays pump fuels. 16/38
Start with 1.9mm BTDC ignition timing. If on a stock coil system you will want to do a coil relay mod to keep the spark strong to handle rich jetting to live on pump gas.
Vintage Smoke Ignition is a points replacement ignition and is great for just that, you must have the rest of the stock charging system
healthy and working. The Vape (powerdynomo) CDI is a modern system and replaces all of the charging system as well. much better in the long run, but more expensive and more work for the first install. (see my posts about installing them in the vendor section)
Try and look on ebay for new oem Yamaha points (for the 1A1 model not 2V0) if needing to stay on them for now, aftermarket points can be hit or miss a lot of the time.

The 30's you have will work great rejetted, if you machine them to fit your manifolds (or buy new manifolds) and with just some minor cable work,you can keep your stock throttle setup with the oil pump once you do a rebuild and test on it.
Need to find some reed stops and trash those Boyesen 2 stg reeds, good on a stock bike only, but too restrictive in upper rpm's and will help keep you in trouble and you have too much of that now...
Use some OEM Yamaha YZ125 reeds or some TDR's with modded stock cages. Get a stock Banshee crossover or go all out with one of my TSR/Barlow designed boost bottles, do not use a Banshee aftermarket boost bottle.

Send me an email and we can talk if you need help.

Chuck

I kind of just have 3.
STG 1 is a mild build with stock or smaller range carbs like 30's on a RD. more torque under the peak power.

STG 2 is more maxed out with more aggressive power, bigger carbs up to 34's, keeping them still reliable with forged pistons with a higher HP
          output, more expensive parts to buy to support sustained higher RPM's.

Then a full race with much narrower powerband but more HP with much more aggressive porting, intake system, custom made chambers and using 36-38mm carbs, race lightweight magneto ignition, setup in a stripped race chassis.

Chuck

I'll keep John in my prayers.

Chuck

A little more than I would like to see, But ok. This can change by a few things, hone grit finish on the cylinder walls, the oil type that is assembled and run for break in and how the break in is run. Proper cleaning of the cylinders before assembly also can be a big one.

I use Sunnen hone with stones made for keyway bores which hones them to 2 tenths of a thousandths round. I like 320 grit for the thin 1mm rings.
I rub the walls with Marvel Mystery Oil on a white paper towel to be sure no grit is left in the walls after washing in a clean mineral spirits parts washer.
Assemble with synthetic oil and I use a aggressive break in of hard wide open short shift bursts after 1 heat cycle first.
Chuck

That doesn't matter, (not supposed to actually), the clutch hub will pull tight against the spacer to set the end play.
If you torque it using the EBC tool to 65ft lbs does it spin fine? If you do a quick mock up with no oil you just can barely feel end play, once you oil everything for final assembly you can't feel any play, is correct and spins freely, your good to go.
Not like the drive sprocket that the splines poke out some.
Chuck

EBC-CT008

On a 400 with a flat headgasket, I would up the torque on the headbolts to at least 23 ft-lbs.
Yamaha makes swing arm shims to adjust the bushing play. I use 50 ft lbs for the swing arm bolt, then adjust shimming until swing arm just barley falls on its own weight. If loose at full torque and you don't have shims... you can cheat a little by belt sanding the inside bushing collar shorter to take up a little play. The frame just will pull in a little, no big deal.
Chuck

I said Yes, I could help him out...planned for Thursday at the moment.
Chuck

Do you have the 3J7 head with the 2R9 cylinders? or STD 1A1 heads using a .50mm copper headgasket?
With foam pod air filters, the mid-range will be lean, because of the Euro/Canadian 2R9 bastard needle jet, its not a replaceable needle jet like the std RD #175. The #284 needle jet is a special one by Yamaha to use the Euro/Banshee crossover tube and intake manifolds.
I would either go back to the stock airbox or do a primary needle jet conversion so you have choices on the needle jet.
The 5L1 needle is a std oem RD400 needle (except 2V0 Daytona)
Chuck

Sounds like stock markings to me.
If an oversize you would see a .25,
50,.75 or 1.00 if were oversize in a oem piston top towards the intake side.
Chuck