ESE's works engine tuner

[Frits Overmars]

could it be that this is causing the overheating issue when used as a race bike and max RPM most of the time?

Many if not most bikes run out of blowdown time.area before they run out of revs. Then exhaust gases enter the transfer ducts, rapidly heating the cylinder.
Maybe you can insert some distance pieces between the cylinders and the exhaust headers, or advance the ignition a bit in order to prevent the rider from revving too high all the time.

don't know if the original KR150 piston has holes in it's skirt, but a KR1 piston has them to lube the bridge between main and aux exhaust ports (which gets realy hot). I'd drill some holes in the skirt.

I've never even seen a KR150 but I used to do some work on the KR1S. The sealing between the common head, the cylinders and around the KIPS bores could be problematic. And they did love the lube holes in the pistons that Jan mentioned. But do not make them bigger than 2 mm.

[JanBros]

The sealing between the common head, the cylinders and around the KIPS bores could be problematic.

indeed.
I made a CNC head for KR1's, and one of the problem's I faced was sealing the KIPS valves. Solved it by placing O-ringed inserts in the KIPS bores in the cylinders. you can read all about it here :

http://www.kr-1s.co.uk/forum/viewtopic.php?f=2&t=11307

[2005bully]

As Speedpro suggests a tight end gap can cause the scuffing of the cylinder at the ring end gap. Another less common cause is be the intimacy of contact between the ring locating pin and the clearance cutouts in the ring itself. Any contact between the pin and the ring should be on the 2 sides of the pin. When checking be sure to allow for clearance changes at operating temp..... Kermit Buller

[marsheng]

Thanks for all the replies - really some food for thought.

One thing I forgot to mention is the squish band is very narrow. 5-6 mm from memory. Could this be contributing to the extra heat being put into the piston crown edges ?

Cheers Wallace.

[Leed]

KR150
"Bike 1 uses TTS and bike 2 uses Spectro Platinum XS. Both bikes are using the standard auto lube system. "

1. why would you use autolube on a race bike? the pump meters out based on throttle cable opening, it doesn't know how much load the engine is under or how many RPM. Another setup variable that can be eliminated... New fuel = new oil, easy to remember NOT a reservoir to be forgotten (accelearation, banking left & right on a low reservoir). All the Formula 3 and Sports Productions kits blank off and remove the oil pump the road based bikes they were based. Spectro Platinum SX is premix only.

2. the bridge(s) between exhaust ports require piston lube holes - 2 each side of main

3. what brand is the pistons?
On the KR-1, pistons evolved into Recessed Ring Pegs due to 'reported' failures: growing or falling (peg then became fully encompassed by ring overlap)
"Generally, when measuring ring end gap, it is most always better to have too much than too little; a tight ring end gap can potentially cause the ring ends to touch during operation (length from thermal expansion), which may cause a failure"
For the skirt to have so many places its picked up, Youd think cyl/bore clearance or run hard not fully warmed.


REID VAPOUR PRESSURE - wobbly
I noted just the other week when installing a new petrol cap for my car, in a very warm garage, how easily vapour was trapped in the tank.
The tank was less than 1/4 full. Minutes later the cap could be removed again with similar pressure blow off.
I see the test procedure ASTM D323 has small cool volume of fuel expanding into a much larger receiver.

Having never opened full drums of race gas - is there much ullage space to pressurise in the first instance?

It seems significant consideration to be mindful of, the freshness of petrol left in your MX or racebike, might have a 5% performance/fuelling/det effect

Today's Factoid: ULLAGE MOTOR to maintain thrust and keep rocket propellant separated into liquid and gas states so that only the liquid is drawn into the motor... kinda the opposite of combustion engines where atom/vapourisation is important?

[marsheng]

KR150

1. why would you use autolube on a race bike? the pump meters out based on throttle cable opening,

The KR has a very clever way of oiling the bigend. There are no slots in the bigend and going premix would reduce the lubrication. Could add some premix to the gas in addition to the autolube.

2. the bridge(s) between exhaust ports require piston lube holes - 2 each side of main

We can try this.

, pistons evolved into Recessed Ring Pegs

The pins are recessed.

[TZ350]

KR150
"Bike 1 uses TTS and bike 2 uses Spectro Platinum XS. Both bikes are using the standard auto lube system. "

Spectro Platinum SX is premix only.

Auto lube pumps don't like shifting premix treacle, you could have cavitation issues on the suction side and limited oil delivery.

[Leed]

what is thin and runny vs thick and slow?
water or ink has a kinematic viscosity ~1 cSt, your blood ~2.43, liquid honey ~950

Castrol TTS Viscosity Kinematic: 43 mm2/s (43 cSt) at 40°C (autolube or premix)
Spectro SX Viscosity: 37 cSt @ 40°C (premix only)

Castrol TTS vs Spectro SX both oils feature similar viscosity, and SX is actually lower = slightly more fluid
Spectro's injector oils range from 57-94 ! some where in the middle is engine oil 0W-30 (66)

viscosity then, isn't a good comparision of 2T oil any more than colour is
is fuel miscibility the separating factor between the two?
and if you have problems with both oils, it not the type or brand that's causing it.

[jonny quest]

What kind of pistons are they? Cam grind and taper may not be good for your application

[chrisc]

Quality racing over the weekend at the Auckland, New Zealand club round!

Here's one of Culley from Team ESE on a Honda NF4 RS125 chassis RG50 bucket. What a beaut!

Click the little blue arrows in the corner of this quote box to see more.

...AMCC Club Championship Round 4 - February 2016....

[peewee]

I thought autolube was mostly for scooters

[husaberg]

I thought autolube was mostly for scooters

Yamaha and Suzuki both used it.
Pretty sure both the TA125 and the TZ350 both originally had it as well. maybe it was the TR or TD?
But simple is best, less to bleed, less to check and less weight to boot.

[Yow Ling]

I think the autolube is unlikley to be the problem there are dozens of RG150's and many other KR150's that dont have this problem. All of Pete Jones's RGs ran TTS with no problems , I run it in my KR with the pump.
I think like others have said the problem might be the piston, its a cheap Thai piston? Probably sourced from china for about $3

With the genuine (ish) Kawasaki part they last for ages, I would go down that path first as the common thing in both these engines is the Piston manufacturer

[marsheng]

I think the autolube is unlikley to be the problem there are dozens of RG150's and many other KR150's that dont have this problem. All of Pete Jones's RGs ran TTS with no problems , I run it in my KR with the pump.
I think like others have said the problem might be the piston, its a cheap Thai piston? Probably sourced from china for about $3

With the genuine (ish) Kawasaki part they last for ages, I would go down that path first as the common thing in both these engines is the Piston manufacturer

Worth a try. I'll see if I can find one.

The holes in the piston seem like a good idea.

Cheers Wallace.

[Bert]

I think the autolube is unlikley to be the problem there are dozens of RG150's and many other KR150's that dont have this problem. All of Pete Jones's RGs ran TTS with no problems , I run it in my KR with the pump.
I think like others have said the problem might be the piston, its a cheap Thai piston? Probably sourced from china for about $3

With the genuine (ish) Kawasaki part they last for ages, I would go down that path first as the common thing in both these engines is the Piston manufacturer

Worth a try. I'll see if I can find one.

The holes in the piston seem like a good idea.

Cheers Wallace.

I recall Mike Chandler talking about cheap Pistons being a major source of issues with VMCC juniors (both KRs and RGs). Swapping back to OEM seemed to resolve a lot of issues. Higher expansion rate on the cheaper option, oil holes may resolve some of this??