ESE's works engine tuner

**TZ350** · 4th March 2009, 15:21

Originally Posted by SS90

The only reason I mentioned it was to point out that larger exhaust port time areas increase cylinder and cylinder head temperatures, and I want to suggest that if the engine was a little "down tuned" ( A little less peak power, and more torque in the lower RPM), ( But can you consider that "Downtuning", or is it really UP tuning...... it's all about perspective I guess) then the engine will run cooler, and be alot easier to ride.

I think your right, this could be a case of "a little less is more".

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**F5 Dave** · 4th March 2009, 17:40

Originally Posted by SS90

. . .
Think of it like this.

If you are cycling (possibly to the pub), and you are breathing only through your nose (not getting enough air), you will overheat, as your "pumping losses" are increased.

O.K, the human body is not a pump, but I think it's a nice example, as we can all relate......

If you where then to start breathing through your mouth, and allowing your body to get more air, you then become more energy efficient, and you will in turn run cooler.

An engine (particularly a two stroke, as you all know is just a pump), if you restrict the amount of intake ( to a point that is too far below optimum), efficiency will go down, and temperature will increase.
. . .

Um. . .actually I don't think that is a good analogy. Yes I see the 24mm carb as a restriction, but I still don't see it as a source of extra heat. The heatsource is reliant on the calorific value of the petrol being burnt at a particular efficiency, & then the efficiency of how that heat is dissipated determines how hot the engine remains after doing set work. I do however agree about the height & size of exhaust port as that falls into both columns.

Are you saying that a smaller carb increases the efficiency that gas burns? . . . or how it is dissipated?

ok so just to be a nit picker 'cause I'm a bit of a krunt, I don't think of an engine as just a pump, particularly not a 2 stroke with an expansion chamber. For 2 reasons. Let's see if we can all name them (and that's is disregarding the whole thermodynamic side of an engine).

**speedpro** · 4th March 2009, 18:20

Interesting statements being made here. I have to side with F5 in questioning the "smaller carb making things hotter" idea though.

Port timing, welllll . . . . . where to start? I've run a piston port TS100 with 200deg of exhaust port and 200deg of intake and a 32mm carb. Somehow or other it was a tractor but still made 19.9rwhp at about 10,000rpm. The dyno curve was big and fat.

I've run 200deg ex on a MB100 with a 28mm keihin and it made 19.9rwhp with a big fat powerband as well with over 14hp between 9000rpm and 13500rpm.

I've run RG 50s, piston port and full reed valve, with in excess of 200deg ex port timing and they both made a nice 10+hp.

My best MB had about 190+ ex timing, 4 petal reed and the same 32mm carb and it made a real good 22.5rwhp with a huge wide powerband.

I haven't dyno'd the latest MB but it is VERY good and has I think even less port timing than a standard MB. There has been a bit of careful porting done though.

**Buckets4Me** · 4th March 2009, 18:21

who is a nip pikking krunchy bar then

hay how about this
why dont you coat the copper inside the head with ceramic (the old ceramic coating creats HP)

but not a very thick coat just thick enough to protect the copper from discolouring and changing it's heat absorbing properties but not thick enough to stop the heat getting to it

now that may stop you having to take the head off and polishing it between races

round and round we go ????
just a thought

also what about the 4 studs could they be the problem at Taupo with the siezures ????? ( seems like a valid point how to test how to test. without spending any money or time making new thinner studs)

back to it then keep making my next engine better

**speedpro** · 4th March 2009, 18:29

The studs question. I assembled the new MB with a bit less than .002" and carefully ran it in. It has usage marks front and rear and that's it. I presume the suggestion to use thinner studs is to deliberately weaken them and therefore allow the motor to expand with heat. What would be interesting would be to clamp a barrel to something real solid with the head on top and slowly up the torque on the studs while measuring the bore. Then you would see if the bore distorting due to increased clamping force was the culprit for the piston damage. I personally don't think so.

**TZ350** · 4th March 2009, 18:44

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In one of the many articles I’ve read recently it talked about pistons seizing from to much clearance as they have reduced thermal contact with the bore.

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**Yow Ling** · 4th March 2009, 19:19

I have an old Gordon Jennings article where he belives most seizires are caused by worn rings, His thoery is worn rings give rise to blow by or gas leakage which interferes with the integrity of the oil film on the piston and bore making an engine with worn rings more likley to seize. He also recomends running as much oil as your ignition can stand.

Running fresh rings makes sense in that they are the means for the piston to transfer heat to the cylinder walls. If you are interested I can scan the atricle and post it up

**speedpro** · 4th March 2009, 20:00

Years ago Bob Haldane did an experiment with some Yamaha 2 stroke. On the dyno it made more and more horsepower the more oil they had in the mixture. Makes sense. Oil is a lubricant and as we all know you can't go wrong with more lubrication. The other purpose of oil is to help seal the piston/rings to the bore

**TZ350** · 4th March 2009, 20:03

Originally Posted by Yow Ling

I have an old Gordon Jennings article where he belives most seizires are caused by worn rings, His thoery is worn rings give rise to blow by or gas leakage which interferes with the integrity of the oil film on the piston and bore making an engine with worn rings more likley to seize. He also recomends running as much oil as your ignition can stand.

Running fresh rings makes sense in that they are the means for the piston to transfer heat to the cylinder walls. If you are interested I can scan the atricle and post it up

Yes please, that would be interesting to read.

**TZ350** · 4th March 2009, 20:18

.

How strong is a cast iron liner? When I was reconditioning engines and needed to fit a sleeve we would bore the cylinder to size and sit the sleeve on top. Then place a round thick (2") steel block on top of the sleeve. Then use a sledgehammer to drive the sleeve down into the block. Some times when the interferance was a bit tight the buggers were realy hard to drive down, cracked a few blocks, never broke a sleeve.

When I was running an RD350 I made up a jig from two heavy plates with studs that a cylinder could be clamped between. With the assembly all correctly torqued up the cylinder could be honed or rebored. The cylinder would then be perfectly round and parallel when fitted to the engine. Possibly its something I should do again for the GP.

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**SS90** · 4th March 2009, 21:17

Originally Posted by TZ350

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How strong is a cast iron liner? When I was reconditioning engines and needed to fit a sleeve we would bore the cylinder to size and sit the sleeve on top. Then place a round thick (2") steel block on top of the sleeve. Then use a sledgehammer to drive the sleeve down into the block. Some times when the interferance was a bit tight the buggers were realy hard to drive down, cracked a few blocks, never broke a sleeve.

When I was running an RD350 I made up a jig from two heavy plates with studs that a cylinder could be clamped between. With the assembly all correctly torqued up the cylinder could be honed or rebored. The cylinder would then be perfectly round and parallel when fitted to the engine. Possibly its something I should do again for the GP.

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What you refer to here teezee, are called "Torque plates".....

Big, heavy, air cooled, steel lined, notoriously hot running engines (Mr Harley davidson, I'm looking at you.......) can only be bored and honed using torque plates, as, when the engine gets hot, the cylinder goes out of round (due to the fact that these have very long studs, (which, incidently are wasted, as I described....), and when the engine goes from hot to cold (a height difference of some 20thou in terms of height), the cylinder gets "squashed", and goes out of round, leading to more heat related problems (much like TeeZee is experiencing)

F5, questions my belief that the size of the carb is causing more heat problems, and, rightly so..

Perhaps if you think of it this way.

There is a point where the carb is just too small (as there is a point where a carb is just too big (opposed to being 1 or 2 mm bigger than the opitimum, and having no advantage/disadvantage (other than a larger induction "roar")

I suggest that the carb is on the side of "too small",and, as such, is restricting more than just the power of the engine.

What f5 points out in regards to calorific values is clearly correct, however, this engine is at a stage of "increasing returns" in regards to improved cooling of the entire engine plant, and every little thing would help.

Mind you, he can't change the carb size... so talking about it is purely academic.

I will however, alter by my statement to say, that a carb that is on the side of "too small" (opposed to just "smaller") will make engine run hotter.

But, to get to where I was heading with this concept.

My thought is this.

I have referred to the idea that (possibly) the primary compression is too low, and I have quoted "losses made by too bigger crankcase volumes (exceeding ratios over 1.5:1) at given RPM can be more than compensated by correctly tuned ex and intakes"

Now, I know that the modern tuning methods use 1.5:1 as a constant (because, well, this rule is correct)

But, maybe the engine is (due to the fact that material has been removed from the intake side crankweb ( incresing the volume of the crankcase, possibly making it lower than 1.5:1, and losing efficiency)

Or, more to the point, due to the fact that the intake system is not "properly tuned" (because, due to the rules, it is too small), maybe a ratio of OVER 1.5:1 is applicable for this situation.

Now, I know that this "increase the primary compression" is a very old concept, and may well be treated with some disdain, but, in my opinion, you need to come up with a way of compensating for your intake size deficit.

**SS90** · 4th March 2009, 21:33

Originally Posted by Yow Ling

I have an old Gordon Jennings article where he belives most seizires are caused by worn rings, His thoery is worn rings give rise to blow by or gas leakage which interferes with the integrity of the oil film on the piston and bore making an engine with worn rings more likley to seize. He also recomends running as much oil as your ignition can stand.

Running fresh rings makes sense in that they are the means for the piston to transfer heat to the cylinder walls. If you are interested I can scan the atricle and post it up

OK, now that someone has brought up this, I would like to bring up another idea...(sorry Tee Zee, but.....)

What are the gains (in your opinion) that you are getting from having a single ring piston?

As Yowling correctly points out, the rings are a means of the piston transferring heat to the cylinder wall,

.......and you only have one....

Now, using a modern "high silicone" piston, is a great idea, but, the only real advantage of having one ring, is the fact that you gain more RPM (and not much else)

There are alot of myths around single ring pistons, and alot of these start in bar rooms and pit lane.

I would like to suggest that having one ring on a piston in an engine that only revs to 10,000 or so, may well be a deficit, particularly in terms of heat dissipation.

Infact, I believe that you would only get tangible gains if the engine was revving to say......12,000 and up!

But again, if I am right, this would only be part of the solution, as it is a contributing fact, rather than a primary cause.

**SS90** · 4th March 2009, 21:57

Originally Posted by TZ350

Certainly a lot to think about here.

I have come to understand that tuners often spend much effort tuning their motors up with ports and pipes etc., then have to reduce the power output by tuning their engines down with a rich mixture so that the engines waste heat from that extra power does not overwhelm the (air) cooling system.

From this I understand that by leaning out the over rich mixture I will be able to use more of the power my motor can make from the modified ports and pipe if I can improve the cooling system.

To improve the air cooling system on my motor I need to think about the total distance from the combustion chamber surface to the fins. Ie the total mean thermal path and how to shorten it.

Port timings I have been using.

Short Track Ex opens 86 ATDC 188 Duration.
............Trans opens 116ATDC 128 Duration.
or.........Trans opens 114ATDC 132 Duration. to widen the power band.

Short Track Ex opens 83 ATDC 194 Duration.
............Trans opens 115ATDC 130 Duration.

Taupo Track Ex opens 81 ATDC 198 Duration.
.............Trans opens 114ATDC 132 Duration.

Started with a pipe from a RG250 then modified it to the RM125 specs found in Gordon Jennings book. (A list of books that can be down loaded from the net appear earlier in this thread).

Interestingly the port specs below are much like what you sugest.

Suzuki RM 125 Ex opens 86 ATDC 188 Duration.
...............Trans opens 114ATDC 132 Duration.

Honda RS 125 Ex opens 86 ATDC 188 Duration.
................Trans opens 115ATDC 130 Duration.

It might be Gordon Jennings et.,all and the approch I have followed from them is a bit old school.

I see current trends like The Wobbly port/pipe specs are for shorter durations. ie., Ex opens 87.5 ATDC Trans 116.5

Speedpro has just finished a Wobbly spec port/pipe setup and his bike runs realy fast.

I don't know why a smaller carb would cause a two stroke to run hotter, will have to find out.

This is buckets, having a go, finding out, and trying it out is all part of the fun, with my old TZ I could never have afforded to experiment like this.

.

Ok,

Taupo, 198 ex 132 transfer........

Hmmmm, and Taupo was where you had your heat seizure related damage......and these are the highest timings you have run....

Lets put that simply......

The same track that you experienced the most heat related problems, is the same track you ran the highest ex port time areas.......

I'm seeing a pattern here, anyone else?

Can I also point out that I question the wisdom of changing the port timings for an individual track.

Wouldn't it be more advisable to lower or raise the squish too suit (allowing more over-rev for longer, faster tracks)

This in itself will cool the combustion chamber.