Symphony of destruction

[Kris V]

Hey Kris...so is there any truth in needing a timing curve to this whole "Turbo Thing"?


Yes there is. I use a Dyna two stage retard box for the turbo. Along with a pressure switch in the intake manifold that actuates the two stages of retard. I retard the first stage 18 degrees and second stage at 22 degrees and the results are!! It also keeps the detonation down to a dull roar.

[Kris V]

I'm in.

I`m in also now that the fire is pretty much done. No scenery but a nice road.

[49er]

One thing you could check - unscrew the front (spigot? tube? - Keihin call it a 'mount adaptor' in the FCR book), and measure the inside (venturi) diameter of the carb. If it measures up to 33mm, then you can upgrade your carbs to 33's for a relatively small cost - and 33's will work better on an 1100 than 31's!

The jetting problems I was having (IIRC - it was 20+ years ago!) were that I could get the top end spot on, but then it was way too lean below half throttle, or I could get the bottom end right, but then above half throttle went way too rich - until full throttle, which jetted OK! Changed the carbs to 33's, and the problems all went away!

I may end up raiding the air jets off the CR's for the Duc, so if I do, I'll try and remember to check what needles are in them...

Sudco do a pretty good job of their jetting. The FCR's I bought (from ca-cycleworks) were damn near spot on out of the box. Even had the idle speed set right! ...But because I've got new headers as well, I need to faff around a little...

Yeah, It would be handy to know what you've got working, but it really does depend on the state of tune of each engine you're comparing against to be of value. The needles I got with the carbs are YY6, YY7 & YY8. The PO had the 6's fitted, which are the richer set, only 2 down on the richest available in the 7 clip range. And this needle range is suitable for up to 33's.

I will measure the bores. It would be easy to go 33's as well!

[Steveb64]

Yeah, It would be handy to know what you've got working, but it really does depend on the state of tune of each engine you're comparing against to be of value. The needles I got with the carbs are YY6, YY7 & YY8. The PO had the 6's fitted, which are the richer set, only 2 down on the richest available in the 7 clip range. And this needle range is suitable for up to 33's.

I will measure the bores. I'm sure it would be more cost effective to do batch machining throughout the range, but I doubt that serious tuners would expect to find that on this type of carb. My transitions were smooth where the spigots met the bores. I would have a step on my carbs if I went to 33 spigots, unless I did some radical machining, like increasing the spigot depth into the body. Not really interested in going there!!

The join/transition on mine was smooth with the 31mm inserts fitted - they had an internal taper from the join to the end. You should (if your ID=33mm) just be able to buy some new 33mm inserts - I guess from Sudco. ...Just checked, and it looks like it. They call them mount adaptors, but when you go to the parts list, they don't give much info - just to 'call'.

My thought is that the different venturi sizes are achieved by changing the 'mount adaptor', and relying on the large range of jetting available to tune around any odd flow dynamics. ...and looking at the parts list, it looks like there's two sizes of throttle bodies - small (26-33mm) and large (35-39mm), so that would follow my thoughts.

When I was doing mine, I lived in rural NZ - and it was a long time ago - and there wasn't a lot of Keihin parts available, so I got a local jeweller (who happened to be a master craftsman watchmaker) who was also a mates dad, and liked doing stuff on a lathe, to make me some, as the thread is really fine where they screw into the carb body, and I didn't trust the local engineering shops to do a decent job. He did a damn fine job too!

[Dave8338]

Hey Kris...so is there any truth in needing a timing curve to this whole "Turbo Thing"?


Yes there is. I use a Dyna two stage retard box for the turbo. Along with a pressure switch in the intake manifold that actuates the two stages of retard. I retard the first stage 18 degrees and second stage at 22 degrees and the results are!! It also keeps the detonation down to a dull roar.

I'm thinking of going the same route with the 'Bird. Say 11-12< TDC at
0-8-psi and back to 9-10 at 9-18psi. The car has a knock sensor and a PIP on it but that just puts the brakes on a little too quickly for me. When temps are 60+- degrees and about 80+% humidity the thing will pull like a frieght train all the way to redline. There is a 3-stage boost controler that can be set for various driving and that with some real control on the timing and things could be a blast.

Winter project?

[posplayr]

RustyBronco Posted this link; something to consider. These plugs are kind of like a "pre-ignition fuse"

http://www.strappe.com/plugs.html

Platinum and gold-palladium alloys can survive the combustion chamber environment as very small wires, and in that rests their great advantage. Electrons leap away from the tip of a small-diameter, sharp-edged wire far more willingly than from one that's fatter and rounded. So the fine-wire plug requires less voltage to form a spark than one with conventional electrodes, and the difference becomes increasingly biased in the former's favor as hours in service accumulate and erosion blunts the iron-alloy electrodes. There are, of course, drawbacks with precious-metal plugs: they are more expensive, and they are very sensitive to excessive ignition advance. The overheating you get with too much spark lead effects plugs' center electrodes before it can be detected elsewhere in an engine, and when subjected to this kind of mistreatment fine-wire electrodes simply melt. In one sense this is a disadvantage, as it means the ruination of expensive spark plugs. Seen in another way it's a bonus feature: it is better to melt a plug electrode than an engine

[49er]

RustyBronco Posted this link; something to consider. These plugs are kind of like a "pre-ignition fuse"

http://www.strappe.com/plugs.html

Platinum and gold-palladium alloys can survive the combustion chamber environment as very small wires, and in that rests their great advantage. Electrons leap away from the tip of a small-diameter, sharp-edged wire far more willingly than from one that's fatter and rounded. So the fine-wire plug requires less voltage to form a spark than one with conventional electrodes, and the difference becomes increasingly biased in the former's favor as hours in service accumulate and erosion blunts the iron-alloy electrodes. There are, of course, drawbacks with precious-metal plugs: they are more expensive, and they are very sensitive to excessive ignition advance. The overheating you get with too much spark lead effects plugs' center electrodes before it can be detected elsewhere in an engine, and when subjected to this kind of mistreatment fine-wire electrodes simply melt. In one sense this is a disadvantage, as it means the ruination of expensive spark plugs. Seen in another way it's a bonus feature: it is better to melt a plug electrode than an engine

We used to use gold palladium plugs on the RD Yamis because they were prone to meltdowns. Cheaper to replace 2 plugs than have to do a complete engine rebuild.

[posplayr]

Ray is right. What he is saying is that Bill was running too much timing for the elevated CR with that modded head. The lower octane fuel you used, just lit the fuse.

You've really got serious timing issues when an engine starts pinging at low rpms and low loads. The safe option is to park it up until you address the problem.

http://www.strappe.com/plugs.html

I was reading and rereading this link that RustyBronco posted. It corroborates what Ray and Ian were saying but provides more details. Sounds like we need to figure out where the timing needs to be set and then work mixture and heat range from there.

We cannot stress too strongly the need to give spark advance your closest attention, because excessive spark lead is the most frequent cause of detonation, which is a real engine killer. You can't stop advance-produced detonation with a cold spark plug, nor with anything but a wildly over-rich mixture. Also, excessive ignition advance has a bad effect on performance. We ran a 250cc road racer at the drags a few months ago, and found that retarding the spark about five degrees from the manufacturer's setting raised the trap speed from 106 to 110 mph. Similarly, there's a 125cc motocross machine residing in our shop which runs a lot stronger and cleaner since it has been retimed for less advance, jetted leaner, and been given a hotter spark plug.

[posplayr]

So this is what my plugs looked like after getting back from the trip. There are 4000 miles on those plugs and two different top ends.

There is some soot there although there is some variation across the plugs.

[posplayr]

Closeups of those plugs if it helps

#1 plug ....................

[posplayr]

#2 plug ....................

[posplayr]

#3 plug ....................

[posplayr]

#4 plug ....................

any comments?

#3 plugs seems a little weird.

[rustybronco]

Pos, I would be concerned with #2 and #3. what material do the flecks on them look like; fuel deposits, aluminum?

where is the timing registering on the ground electrode?

http://www.dragstuff.com/techarticle...ark-plugs.html

Reading For Ignition Timing

Ignition timing is directly responsible for the heat in the combustion chamber and therefore the color of the plug’s ground strap and the color of the first few threads on the outside of the plug. The ignition timing can be checked by looking at the color of the plug’s ground strap and the position of the "blue line" on the strap.

for #3...

If you see the porcelain take on a shine then it is time to change the plugs because the glass that is in the porcelain has been melted and has glazed the surface.

***edit***

for #2 and #3

Other Things To Look For

The round flat circular area of the plug at the end the threads should be dark gray or flat black and should not be sooty. If it is sooty then it can mean that your plug has not been tightened enough and you are sucking and blowing fuel and air past the threads of the plug.

Detonation shows up on the plugs as spotting on the porcelain. There are two different types of spotting seen. One type appears as just black spots and the other appears as little bright spots like diamonds. The black spots (look like pepper sprinkled on the plug) indicate a little too much heat on the plug which causes detonation by having the heated plug fire off the mixture prior to the spark firing.

I think it will be best to install those shiny new plugs and re-read them.

***my un-educated guess? you're running very close to the ragged edge.***

[posplayr]

Pos, I would be concerned with #2 and #3. what material do the flecks on them look like; fuel deposits, aluminum?

where is the timing registering on the ground electrode?

http://www.dragstuff.com/techarticle...ark-plugs.html

for #3...


***edit***

for #2 and #3


I think it will be best to install those shiny new plugs and re-read them.

***my un-educated guess? you're running very close to the ragged edge.***

Yea I think I have some plug chops coming in my immediate future. I have the coil mod relay installed, but have not put the Dyna-S back in. I need to do that and set the timing on the front v.s. back as you are right. 2 and 3 seem hotter than 1 and 4.

Of course you realize I had just gotten back from a 2500 mile trip to Oregon which included alot of riding at 3000 ft and above. I normally ride at less than 1000 ft.

Question, can you do a plug chop with a cleaned plug or does it need to be new? I don't mind buying another set of the Iridium NGK's but several sets might be pricey.