Rotax 300 builld

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Scooterdude
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Wed Dec 13, 2017 11:02 am

I don't see a probe anywhere near the exhaust. Air/fuel mixture perhaps?

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RManson
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Wed Dec 13, 2017 7:42 pm

Stampede wrote:
Wed Dec 13, 2017 7:47 am
Do you know the reason for the breakdown?
The verdict is still out on the cause, but I have a few suspicions and am looking into everything. Will post what I find for sure.

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RManson
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Wed Dec 13, 2017 7:44 pm

drunkmunkey6969 wrote:
Wed Dec 13, 2017 10:54 am
RManson wrote:Well, things started off promising.

ImageIMG_6131 by PotvinV8, on Flickr

That looks like a decent dyno setup, who/where is it?
It's the test dyno at Hot Bike Magazine here in Southern California. They use it for product testing, etc. and did a few pulls as a favor for me.

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RManson
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Wed Dec 13, 2017 7:46 pm

Scooterdude wrote:
Wed Dec 13, 2017 11:02 am
I don't see a probe anywhere near the exhaust. Air/fuel mixture perhaps?
Not ruling anything out but things looked good on the air/fuel meter before running the bike on the dyno. We were only planning on making a few pulls to get a power number, not to test and tune as they're not really set up for that, hence the lack of any probes, etc.

holty
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Thu Dec 14, 2017 9:07 pm

i took a friend of mine to chisellspeed this year ofter he had holed a piston and martin put a probe in the exhaust to measure the mixture, he adjusted it the jetting to get it right, followed up with a couple of road tests, until he was happy with it by feel and colour of plug, the dyno operator is a big part of the process of setting it up safe to use, i mentioned in my other reply about egt gauge, my mate fitted one to his before martin set it up, and he keeps an eye on the exhaust temperature now as well, good luck with getting it fixed,
holty

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RManson
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Thu Dec 14, 2017 10:06 pm

Thanks Holty,

Already have a new barrel, piston and head on the way. All for under $100, bearing testament for why I went with this setup to begin with. I overlooked the importance of the stinger size and I think that was the problem. With an EGT gauge, we should have seen that. Suffice to say, I'm adding one of those to the parts list for Round 2!

holty
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Thu Dec 14, 2017 10:12 pm

RManson wrote:
Thu Dec 14, 2017 10:06 pm
Thanks Holty,

Already have a new barrel, piston and head on the way. All for under $100, bearing testament for why I went with this setup to begin with. I overlooked the importance of the stinger size and I think that was the problem. With an EGT gauge, we should have seen that. Suffice to say, I'm adding one of those to the parts list for Round 2!
good man, and thats a very good price, we get crippled with stuff from the states, over here, import tax, im sure you will get it sorted, ive checked my stinger and its 26mm id, i might have to do an upgrade.
holty

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RManson
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Fri Dec 15, 2017 5:51 am

holty wrote:
Thu Dec 14, 2017 10:12 pm
good man, and thats a very good price, we get crippled with stuff from the states, over here, import tax, im sure you will get it sorted, ive checked my stinger and its 26mm id, i might have to do an upgrade.
holty
I would definitely have a look at the stinger size, especially if you have a silencer/end can on it, which I think you do. I'm hearing anything from 3-5% increase of the stinger size due to the end can. I've been crunching some numbers for a new exhaust and the formulas call out a stinger size around 30mm. I'll probably increase that to 31-32mm due to the addition of the silencer, just to be safe.

That's the easy part, however. The hard part is going to be designing a pipe with a 142mm belly with decent ground clearance. As it sits now, the old pipe was 121mm and already caused problems.

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RManson
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Fri Dec 29, 2017 5:53 am

The EGT gauge arrived today from Classic Instruments. These guys do custom gauges for us all the time for hot rods and customs and whatnot, so it made sense to give them a call to get an EGT gauge that matched the R6 cluster. I think it will look pretty good when it's all said and done, and will hopefully prevent another meltdown!

White face, curved glass, black bezel, and red pointer were all custom options.

Purchased a KTM300 pipe to compare with the YZ250 pipe I used originally so hopefully can get the exhaust sorted and back on the road. Easier than building something from scratch and from my calculations, the diffuser, belly, and baffle specs should be pretty close. Will just have to fabricate the header and stinger/silencer to suit. This time using better math! :lol:

ImageEGT Gauge by PotvinV8, on Flickr

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RManson
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Wed Jan 03, 2018 7:06 am

Parts & pieces as things go back together...

ImageIMG_6245 by PotvinV8, on Flickr

ImageIMG_6246 by PotvinV8, on Flickr

ImageIMG_6247 by PotvinV8, on Flickr

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