Symphony of destruction

[49er]

Bill do you have an oil temp gauge on that bike? It sure looks like the damage to the piston is from something letting go and not limited to detonation alone. One thing with welding cast aluminum...the porosity of the weld rarely if ever matches the original casting and as a result will expand at a different rate than the surrounding cast material.

As temps increase, so does the effect of this expansion difference. Add to that the vibration and stress of an engine, internal heat temps of the combustion chamber and compression and it is no surprise that things let go.

Also...do you know if the shop preheated the head to 500-700 degrees first and brought the temps back down slowly to promote penetration and bonding?

If the welder knew his stuff, the weld composition should have been compatible with the head material/parent metal. If there was porosity present in the weld, the operator didn't pay enough attention to cleaning and preheat procedures.

Auto aluminimum heads have been successfully welded to improve cylinder shape/volume for many years. You will get significant distortion which has to be addressed. People who do a lot of this work, will prebend the head so that it straightens during the welding operation. By doing this, the cam bearings remain at their correct alignment and minimal CCing correction work is required. If you just resurface a bowed head, the inner chambers will have lower volumes causing higher CR.

[Kris V]

This is what my thoughts are also, the guy didn`t prep the cast correctly and expansion took over popping the weld off. This guy (the welder) knows nothing of bikes Bill tells me.

[49er]

This is what my thoughts are also, the guy didn`t prep the cast correctly and expansion took over popping the weld off. This guy (the welder) knows nothing of bikes Bill tells me.

From those pics, I'm not convinced that a piece of ali separated from the head. I think that this destruction has been caused through detonation. I believe that Posplayr confirmed that Bill heard pinging occurring whilst he was riding the bike, well before the melt down started. It has been running lean and the increase in CR on the inner pots has started the detonation cycle.

If the repair weld was full of porosity, the chamber temperatures would have elevated rapidly during detonation, contributing to the meltdown.

[almarconi]

This guy (the welder) knows nothing of bikes Bill tells me

Why would you have your motorcycle cylinder head welded by a welder who knows nothing about motorcycles?

[Nessism]

Why would you have your motorcycle cylinder head welded by a welder who knows nothing about motorcycles?

Welding a motorcycle head shouldn't be any different from welding an automotive head. Any decent automotive machine shop should be able to handle it but I'm not so sure about a general purpose welder guy.

[chef1366]

Why would you have your motorcycle cylinder head welded by a welder who knows nothing about motorcycles?

Because I enjoy getting kicked in the teeth.

[49er]

Because I enjoy getting kicked in the teeth.

Bill, it wasn't my intention to put you down (now there's a pun).

I have only posted here so others can learn from your experiences and perhaps avoid the pitfalls and frustrations that you have encountered. Having said that, you are now a far more knowledgeable and credible expert on the subject, having personally endured the experiences.

Good luck with the next chapter. PM me if you need some help.

[chef1366]

Bill, it wasn't my intention to put you down (now there's a pun).

I have only posted here so others can learn from your experiences and perhaps avoid the pitfalls and frustrations that you have encountered. Having said that, you are now a far more knowledgeable and credible expert on the subject, having personally endured the experiences.

Good luck with the next chapter. PM me if you need some help.

Ian, in no way did I take anything you said as a put down. I respect your knowledge and I have proven you right on many occasions.
Now for the 1230 kit! I will not burn this one up!

[posplayr]

Ian, in no way did I take anything you said as a put down. I respect your knowledge and I have proven you right on many occasions.
Now for the 1230 kit! I will not burn this one up!

Just so it is know, Bill and I have very simular motors:

• 1166 kits
• 0.340 Webcams
• 1150 36mm CV's with 147.5 mains
• DJ Needles (Bill setup both sets of carbs)
• 4:1 and 4:2:1 headers
• Pods
• Ported heads

His fried and mine did not as we were doing the near exact same thing on the same ride. The only differences are:

• Bill's L was carrying about about 25-50 lbs more weight (rider plus gear differential)
• Bill had upped his needle 1/2 a notch to lean it out for the higher altitude ridding we were doing at Mt Shasta
• Bill's ported head is not as ported as mine but he has +1.5mm oversize valves v.s my stock 1150 intake valves (+1 mm).
• Bill cams are degreed 110/110 while mine is as recommended 105/107 (We degreed both bikes together)
• Bill has a larger oil cooler than I do
• My oil temp guage never showed I was running hot or anything above about 220-230 degF
• We were cursing through a twisty road at between 15-60 mphs

There really is not much difference beyond that which is scary to me.

[49er]

Just so it is know, Bill and I have very simular motors:

• 1166 kits
• 0.340 Webcams
• 1150 36mm CV's with 147.5 mains
• DJ Needles (Bill setup both sets of carbs)
• 4:1 and 4:2:1 headers
• Pods
• Ported heads

His fried and mine did not as we were doing the near exact same thing on the same ride. The only differences are:

• Bill's L was carrying about about 25-50 lbs more weight (rider plus gear differential)
• Bill had upped his needle 1/2 a notch to lean it out for the higher altitude ridding we were doing at Mt Shasta
• Bill's ported head is not as ported as mine but he has +1.5mm oversize valves v.s my stock 1150 intake valves (+1 mm).
• Bill cams are degreed 110/110 while mine is as recommended 105/107 (We degreed both bikes together)
• Bill has a larger oil cooler than I do
• My oil temp guage never showed I was running hot or anything above about 220-230 degF
• We were cursing through a twisty road at between 15-60 mphs

There really is not much difference beyond that which is scary to me.

Jim, thanks for the comparisons. I wouldn't be too concerned about your bike doing the same thing unless you make some radical change that leads to leaning/overheating. Your oil temp gauge is a fairly good indicator of impending problems. I constantly relied on mine when rallying rotaries, as an early warning tool.

There are some significant differences mentioned above, plus a few that you probable hadn't considered.

1. The difference between a 4-1 and a 4-2-1 system affects scavenging pulses differently, throughout the rev ranges. This means that both your engines would show different AFR's at the same rpms, if you dynoed them together.

2. The degreed differences of the same spec cams along with the different headers can contribute to significant performance/heat variations at certain rpms. Why did Bill not go with Web's recommended degree figures?

3. The differences in porting/valve sizes/seat angles and pocket shape and dimensions combined, are significant when considered as parts of the whole tuning package.

4. On the day, the leaning change of needle position, plus the extra weight Bill's bike was hauling are major contributing differences, especially as you don't know the true CC'c of Bill's combustion chambers.

5. As I recall, Bill also experimented changing the primary air jets on his carbs. Have you done the same, if not, that is another difference.

5. When each engine was assembled, did you have identical deck heights, head gasket thicknesses, squish areas and valve head shrouding relief? Did you both cc your chambers to compare them? How different did they check out?
The one big mistake I see many road bike tuners make is reduce the squish area, at the expense of gaining higher CR with their stock pistons. By doing this, they affect the rate and efficiency of the flame front across the piston crown. To counter this, higher grades of fuel need to be used to stop detonation, or spark advance must be retarded instead. I know that this probably doesn't apply here, but without personally measuring, it's possible to have two engines appearing identical, that DOOOO have significant differences. You do need to establish whether the PO has made an changes to the stock surfaces. This can only be confirmed by exact measurement.
As a matter of interest, what was the difference in compression figures between the 2 engines?

6. At the risk of harping on, altitude changes are one of the many negative side effects experienced by pod tuned road bikes.

[posplayr]

Wow there is a bunch of stuff to consider there. I dont know all for sure, but I will add a few more things to the mix.

It is pretty likely that my cylinders were never milled and my head only had about 0.002-0.004" skimmed off as it only had 15K miles on it and came from an 1100E with a blown crank. So I think my deck heights are pretty much stock save for the milling mentioned above.

I don't know about Bill's, and neither does he; the machinest he used did not seem to have any idea how much he had removed . After that wellding I can imagine alot might have comeoff to make the surface clean again.

One other possibly significant contributor that I just remember is that we were basically doing a jumping off to what is called the "lost coast" on Norther California. The jumping off point was from an old Nor Cal town called Ferndale. They only had oen gas station and it was pumped from a single above ground tank and only had Regular gas (87 octane here in the US) We normally use Premium (91 octane). To compond the problems Bill only has a 3.4 Gal tank and I have 5.(x) so when he is down to his last 1/2 gallon I usually still have 2 more gallons to go. When he topped off with 87 octane, he probably got a full dose with me closer to a 50:50 mix of 87 and 91 octane.

I drove past the last gas station before Ferndale so I guess I'm somewhat to blame for the fiasco as well

[49er]

Wow there is a bunch of stuff to consider there. I dont know all for sure, but I will add a few more things to the mix.

It is pretty likely that my cylinders were never milled and my head only had about 0.002-0.004" skimmed off as it only had 15K miles on it and came from an 1100E with a blown crank. So I think my deck heights are pretty much stock save for the milling mentioned above.

I don't know about Bill's, and neither does he; the machinest he used did not seem to have any idea how much he had removed . After that wellding I can imagine alot might have comeoff to make the surface clean again.

One other possibly significant contributor that I just remember is that we were basically doing a jumping off to what is called the "lost coast" on Norther California. The jumping off point was from an old Nor Cal town called Ferndale. They only had oen gas station and it was pumped from a single above ground tank and only had Regular gas (87 octane here in the US) We normally use Premium (91 octane). To compond the problems Bill only has a 3.4 Gal tank and I have 5.(x) so when he is down to his last 1/2 gallon I usually still have 2 more gallons to go. When he topped off with 87 octane, he probably got a full dose with me closer to a 50:50 mix of 87 and 91 octane.

I drove past the last gas station before Ferndale so I guess I'm somewhat to blame for the fiasco as well

That drop in octane rating at the previous top up was "the straw that broke the camel's back". Leanness, high CR and poor quality gas looks the likely combination.

Glad you came clean with that last sentence. Confession is good for the soul!!

[posplayr]

Glad you came clean with that last sentence. Confession is good for the soul!!

I only remembered as I was writing the last response. We had put in regular once earlier but at higher altitude with no problems.

Ironically if we had been deep into the revs this might not have happened as we would have been well onto the mains.

[49er]

I only remembered as I was writing the last response. We had put in regular once earlier but at higher altitude with no problems.

Ironically if we had been deep into the revs this might not have happened as we would have been well onto the mains.

You spend most of your road riding on the pilot/needle circuits, so you need to establish your tuning safety margins in those throttle positions as well.
When engines are tuned that highly for road use, you are constantly wary of the "Big Bang".

I'm not into living that close to the edge these days.

My formula is: Hemi 2 valve, 1hp per 10 cc = above average performer that can be hammered all day and will live!!

[chef1366]

Darn BFE gas station.