KX Guru Racing

DoldGuy comment:
What chamber volume or CR & width are you running? As Motorrad noted my squish was setup pretty loose (it measured .065") and this is going to be one of the areas I will be testing in the future. From reading some of your replies your not just running the bike for 2 minutes & shutting it down, which makes me curious how it's living with it that tight. Also curious if it's got low CR from a small trapped volume from a long duration smoke hole?

Motorrad:
That's the impression I get from BDI also. A hill shooter that rides the dunes also, if not moreso... Dunes are on/off the gas more than a desert race... Pure dunes motors don't live long in open desert. But still interesting...

Kaw Rider comment:
if you take a head at .065 and cut it down to .030 if will run cooler.

Motorrad:
Just to be 100% clear. The numbers you guys are stating is total squish? That is what I'm referring to.
I have heard people say squish before and they were only talkig about the step in the head (gasket surface to out edge of chamber). I know my head was about a .028 step.....

My comments:
Motorrad is referring to his first engine build..

Motorrad:
First time.. I could have... and should have had controll... there is no excuse for me not testing it before I took it out... "new" motor by big name guy or not....I had the pipe off, to look at piston and bore.. I should have leak down'ed it then and there.... We all have our moments of stupid and Gullable....
Second time.. well hard to forsee (at the time) exploding bearings. etc etc etc... (yes I leak down tested when It got to me, and passed)..


On a good note...

Got all my KIPS parts in at the dealer today... as most needed replace... (center flap, idle gear, and the alum insert guide thinggys).. You wouldnt believe how much slop there was... even though it all didnt look "that worn". Put in the idler gear retainer (alum piece) and you can see the gears still from the gaps!.. Yikes.. new one.. no gaps. Also had to order O-rings, the ones in it were too large... Quick touchup with a flapwheel on the center flap to get rid of most of the casting BLaH.. Dont go too far... would take away alot of material to get it all....


So as soon as KAW Riders fancy shmasy Stealth kips bolt hits my door... thats all done and ready to bolt on.. GOTTA Go stealth... Its the only way!.. More fun when you beat the doors off guys at the hill... and tell em its a stock motor.. .

Found out after having my crank for a month now, my crank guy still hasnt touched it... since he is in the middle of doing all his road race stuff... UGG.... but he promiced to get on it this week... and also balance it for me CHEAP for waiting... Which IN hindsight... is probly a VERY good idea... The crank stuffers, and wiseco piston combo probly has the balance factor thrown WAY OUT IN LEFT FIELD...

After arguing with wiseco for the past week... I broke down and ordered 4 sets of new rings (found them for $26 a set)..
They keep telling me that .022 is fine... I keep saying its not.. as thats almost .010 more than they reccomend..... round in a circle.. trying to get another set of rings out of them..

I know the Bore is correct... so it only leaves rings to be the issue...
But the ones that came off my "old" piston read at .014 so.... hopfully 1 out of 4 will also...

Not going to get in a debate of polished vs non ... I like mine this way...
Really hard to get the camera to do it justice...

Was thinking about it today.. And I dont think I have ever seen anyone on here mention the use of a crank Jig..
Since the Big K5 cant use the (crank pulling tools).. being a Circlip on the primary side...
It really is your best friend!
Extra points if you can tell me what kind of motor that is....
(1972 Bultaco persang 350cc)

nothing mechanical has happend latly
Sooooooo.....

A word on greasing seals.
We all know you should grease your seals... (little smear of grease between the sealing lips before you toss in the waterpump, kips, crank, etc etc etc..

But how many of you know that alot of grease's out there will actually deteriorate rubber and nitrile?!
I learned long ago, a trick from the auto industry... working on A/C...

the trick to keeping a long service A/C system... is to grease all the little o-rings...

But with what?!
Yep. Dielectric grease...
It wont deteriorate rubber. It actually conditions it!.

I have since moved this trick over to building motorcycles, and any other sealing application.. and have had great results over the years...

Got some good news from my crank guy today....

checked the balance and it fell at 58%...

thats with the stuffers, wiseco piston, and OEM wrist pin, and rod goodies....

Very happy to hear that.. as it doesnt need to be touched.. I thought I was going to be WAY out in left field with the stuffers on there..

Should get my crank back in the next few days.. Yippie...

Me:
Piston lightening

Motorrad:

Just crunched some numbers....

I can shave 30G and end up right at 60% balance factor... muahahha..

Okay.. did somthing about the kips today..

Marked it with a Marker where it started to cover, and the end of travel... so I knew where to remove material..
Shaved the back (lower part of taper) down to where I was happy with it.. then blended....


Didnt touch the high portion (of the taper), as it directs out of the CYL.. and into the resonator.... and didnt want to cut on CYL... and dont know enough about how the resonator effetcs the motor to change the ammount of exhaust going in and out of it....
Cut on left, uncut on right

Before
After

Got me some Nifty parts in the mail today!.

Thanks Kaw Rider..

It looked great right out of the box... But me.. being the way I am (obsessive compulsive).. I gave it a quick bath in some gun blue....

PowerFiend:
I'm interested to know what you think of the crank stuffing then with the stock cylinder. Stewart seemed to make a big deal about how the cylinder needed to be ported when you stuffed the crank.

Motorrad:
Unfortunatly the motor didnt have enough time on it before teardown to give a good review on the stuffer... My porting now, is just cleaned up from stock, nothing changed as far as duration, size etc (its now matched to teh cases, and a few Woopies taken out of the transfers, as well as the dividers being same size now)... but thats about it... so it should still be a good base referance for stock porting... and Ill make sure I post up how the stuffers effect it for ya..

Kaw Rider brought somthing to my attention today over the phone.. and after both of us taking measurements it confirmed it.

The V3 reeds, stops compress quite a bit once put into the cyl..

Mine were actually stuck this way (heat from the motor, caused the stops to have a memory)..

SOOO. to attempt to fix this issue.. This is what I did today..

First to fix the memory problem, I put a piece of alum plate betwen the peddles and the stops, heat the stops up really fast with a heat gun, and bend outward...
Mine measured 1.36" (and still shrunk once pushed in CYL)... Kaws new ones measured 1.5" (going off memory here).. after I reshaped them, mine are now at 1.65... (this is measuring inside to inside from one stop to the other).

So after that. I needed to see about fixing the problem... Well I am not a huge fan of reed spacers, well atleast not the 3/8" ones.. Not going to argue one way vs the other..

SOOOO.. I took a reed spacer and milled it down to 1/8" not enough to mess with stuff much.. I also threw a bit of taper on it to clock the reeds more tward the top of the CYL.. (not much, thickness of a a&N washer wink )...

Initial cut, to see if Taking to 1/8 would be too much. , Taper cut,/final cut after this ..
I havnt measured to see how much this fixed the problem yet. as I plan on looking at possibly trimming the end of the stops as well... (and a 7mo old child decided I dont have time to measure tonight..)