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Dyno Result

Old 04-07-2013, 05:57 AM
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Dyno Result

I decided to get a run done on the Dyno as I have been playing around with my jetting by the seat of my pants and wanted to know for sure what it looks like. This is my first ever Dyno run. Nether had one before on any bike though have witnessed a few. I did make it clear to the Dyno tech that I was not interested in my max HP (bragging rights rubbish) and that I do all my own carb work and am mainly interested in my A/F. I don't think the guys I used would have altered the results and have just let the Dyno do it thing as well as it can. It was a rear wheel roller type machine.

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Red line is the Right hand side pipe which is giving out 104.77bhp and 97.16Nm torque.
Blue line is the Left side and giving out 106.1bhp and 98.46Nm torque.

It actually turned out to be two runs, I think the operator done one run each, swapping the probe in the exhaust around. He only had the one probe.

If I go by the Red line (right exhaust) for the AF then I think I done a reasonable job by the seat of my pants though it could be a little richer on the pilot circuit and maybe a tad leaner on the mains, which will also bring the middle at 6-7 thou up slightly. I'm thinking standard mains 175 front and 178 rear and possibly upping the pilots from 48 to 50's. But for now I want to leave as is as the bike rides nice and I want to sort out the following first with the Left exhaust.

As you can see the Blue line on the AF is messed up. I think this could be to do with my left hand link pipe. Where I have used and SP1 exhaust I have had to cut the 45 degree bend of the end of the link pipe on the can and fit a 90 degree mandrel pipe from the link to the header outlet. Unfortunately at the time it was a bit of a bodge and I ended up using a mandrel with IIRC a 45mm diameter, so smaller than the storms and probably restricting things.

My question is would this cause the upset in the AF reading like this? What else could cause that reading? And how would the right hand exhaust effect the reading with the probe in the left as they are linked. All opinions and suggestions welcome. I know Markus has his own Dyno so it would be interesting to get his opinion in his usual thorough and constructive criticized way.

My Carb setup is as follows:

Factory Pro Jet Kit
Standard filter and running two standard long velocity stacks.
Front carb
178 main
48 pilot
needle clip 2rd from the bottom
standard 10though shim
A/F done by ear
rear emulsion tube the same as rear

Rear carb
180 main
48 pilot
needle clip 2rd from the bottom
Added 20thou standard 10though shim
A/F done by ear

I am running SP Arata exhausts with no baffles in the upswept position like on the SP's RC51.

Unfortunately I don't know what the exact turns on my fuel screws are, as it's hard to count them on the screwdriver and listen to the way the bike runs at the same time. But when I blip the throttle my rev needle is smooth with no fluctuations and the bike idles perfectly at 1000rpm once fully warmed up. It will idle at 2000 with no choke when cold and slowly creep up to 1000 where I have the idle set once fully warmed up.

I look forward to your suggestion and opinions guys.

(:-})
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Old 04-07-2013, 09:50 AM
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I can't see how the air fuel ratio could be possibly different between the two pipes. The only way would be if you had a major exhaust leak that was letting outside air in. Again, I'm not sure that could even happen.

Maybe it was just different engine temperature? I assume he made a pull, fiddled around a bit, and made the second pull. That could explain it and also help you a lot in your tuning.
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Old 04-07-2013, 10:25 AM
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I also can't really see how one side would be different than the other.

One other thing you might want to try is going back to the stock front emulsion tube as you are running two long stacks.

That mod was to help cure the bike going rich in the low-mids (or why I plug lift holes) with the short stack. So going back to stock might give you enough extra that you won't have to change the pilots.
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Old 04-07-2013, 11:50 AM
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The emulsion tube is a very good idea, I was wondering about that. It could bring the low end back to a less lean level. Yes the more I think about it the more I think you are right there. I shall do that. I have had 50's in the past and it was just too much, only 1 to 1/1/4 turns on the fuel screws.

Jamie the guy did not pull the carbs, I just turned up and had a couple of runs done. I only wanted the one but he ended up doing the two. I did ask him first of all if it was possible to tell the differances between the front and rear cylinder on the results which I expect would not be a problem if the header pipes where not linked. I'm not even 100% sure if had the probe in each end can for both the runs. He could have just had it in the right can for both runs.

Just seems very odd to me the way the AF shoots lean at 5 thou and it happens to be the side where I have the smaller diameter mandrel. I'm thinking the next thing to do then is to just repace the front emulsion tube with the standard and then go to an exhaust place and get a proper pipe (mandrel) made at the 51mm diameter and have it flared each end to fit correctly. Currently the mandrel fits inside both ends and I know for sure there are no exhaust leaks.

I did notice last time I had the carbs off that the rear carb rubber was looking a bit tired where I have pulled them on and off so many times. I put some sealant around the inside of it last time I put the carbs on. I may replace this as well as a precaution.

It does seem odd the way that AF shoot up.

Thanks for the replies guys.

(:-})
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