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aj201280

New Rev 3 Mikuni Carb?

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Just thought I would add my 10p worth to this thread.

Bought my 06 250 new and have had no problems at all. No fuel leaking, no downhill starting problems noticed and no loose bolts from new.

Before the first shake down ride, checked everything and found nothing loose. Checked everything after the first ride and nothing loose.

After the second ride, took the necessary bits apart, cleaned and thread locked where needed. I would do this to any new bike and most handbooks would also recommend checking everything for tightness after the first ride as a new bike will need a bedding in period for tolerances to be taken up and stresses and strains put through the wheels, suspension, chassis and engine assembly.

I think the PDI on my particular bike must have been thorough (as all PDIs should be) and the carb well set up with good components fitted as standard from the factory.

The only gripe I have had is that the standard kill switch was sometimes sticking in the housing so I changed it for a Yamaha style one which is much better in design re prevention of dirt and water ingress.

So I hope this shows the other side of the (10p) coin. Had my bike been problematic it would have gone back to the dealer to give them a chance to rectify, after all the goods they sell should be fit for purpose and you have the usual statutory rights.

Just as an aside, I have a few tips for this model which have been gleaned from my own experiences of ownership and will post these shortly.

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I think i read somewhere that the carb drilling mod which does stop the spillage can also cause flooding slightly more easily, and Lampkins now only recommend it if you are doing the scottish or such like where every drop of fuel counts.

That will be me then!!

Bike wouldn't start last night, kill switch had got stuck causing the plug not to spark! This is a bike that is brand new!

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Boof' most brands of bike need to be tweaked for the SSDT, one of the best things to do is to replace the factory kill switch with an aftermarket one, I think the Yamaha MX ones are the best or is it the Honda one?. :chairfall:

John Lampkin used to have a list of SSDT mods on his website but I can't find it now http://www.beta-uk.com

PS

It's best to have these little problems now and not in May :bouncy:

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Found the set up info by doing a search on TC. I'll post a link on a new thread for those that might want to know.

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The sticking kill switch is well known, just enlarge hole in outer casing.

The Billy t carb mods (I've used these on 5 betas now) can be found here is you search.

If you're stuck - PM me & I'll send pdf.

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Been meaning to take some pictures of the Mikuni carb mods as there is always questions about it one here, hope they will help someday

The pictures are of my carb with mods carried out by BVM earlier this year. The first two pictures show the float extension bowl for the rev3 along with the main jet shroud the kit comes with. The Extension kit has stopped my bike pinking on climbs, something it suffered badly from before fitted.

The 3rd picture shows the exhaust side Atmosphere pipe bent towards the barrel slightly which allows the pipe to run free and not touch the exhaust. From new the pipe was always bent shut due to it being to close to the Exhaust, it was bent using a BFH tapping lightly at a time so not to break it.

4th picture shows the tang levels which have stopped the fuel from spilling out of the carb, looks about the same height as Billy T's picture on the R2W site.

5th and 6th pictures show the drilling mod from both angles, this is explained on the R2W site as well.

Edited by Betarev3
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Excellent pics, this post should be made a 'sticky' in the Beta forum.

The 5th pic shows the drilling in a different place to where JLI's did mine 2 or 3 years ago. Just above the new hole (arrowed) is a raised/flat nipple with an indent preformed into it - this is where mine was drilled out.

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Been meaning to take some pictures of the Mikuni carb mods as there is always questions about it one here, hope they will help someday

The pictures are of my carb with mods carried out by BVM earlier this year. The first two pictures show the float extension bowl for the rev3 along with the main jet shroud the kit comes with. The Extension kit has stopped my bike pinking on climbs, something it suffered badly from before fitted.

The 3rd picture shows the exhaust side Atmosphere pipe bent towards the barrel slightly which allows the pipe to run free and not touch the exhaust. From new the pipe was always bent shut due to it being to close to the Exhaust, it was bent using a BFH tapping lightly at a time so not to break it.

4th picture shows the tang levels which have stopped the fuel from spilling out of the carb, looks about the same height as Billy T's picture on the R2W site.

5th and 6th pictures show the drilling mod from both angles, this is explained on the R2W site as well.

Why is it that you buy a carb from the manufacturer who has been doing this for years and then have to modify them. :thumbup: Would you buy a BMW then start drilling holes in the EFI to get it to work right?

I had the same problem with the Dellorto VHST on the Sherco 4T :beer:

Seems to me we accept poor equipment in trials far too easy?

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Been meaning to take some pictures of the Mikuni carb mods as there is always questions about it one here, hope they will help someday

The pictures are of my carb with mods carried out by BVM earlier this year. The first two pictures show the float extension bowl for the rev3 along with the main jet shroud the kit comes with. The Extension kit has stopped my bike pinking on climbs, something it suffered badly from before fitted.

The 3rd picture shows the exhaust side Atmosphere pipe bent towards the barrel slightly which allows the pipe to run free and not touch the exhaust. From new the pipe was always bent shut due to it being to close to the Exhaust, it was bent using a BFH tapping lightly at a time so not to break it.

4th picture shows the tang levels which have stopped the fuel from spilling out of the carb, looks about the same height as Billy T's picture on the R2W site.

5th and 6th pictures show the drilling mod from both angles, this is explained on the R2W site as well.

Why is it that you buy a carb from the manufacturer who has been doing this for years and then have to modify them. :bouncy: Would you buy a BMW then start drilling holes in the EFI to get it to work right?

I had the same problem with the Dellorto VHST on the Sherco 4T :wall:

Seems to me we accept poor equipment in trials far too easy?

You are exactly right. I started a post off about this when I picked up my new bike. I was making the point that the trials community as a whole should not accept poor quality, but people got to obseesed with trying to work out which bike I had bought, when the problem is the same with all of them (except maybe one). They all need modifying /fixing before you use them, and you shouldn't have to.

I got a new VW in September, and I didn't have to improve anything on that, and when I did have a problem VW couldn't of been more helpful and apologetic. I certainly didn't get my spanners out for the car. So really you shouldn't have to for your bike.

The trouble is we are all so desperate to ride them that, it is sometimes quicker and easier to sort them out yourself.

This said when I did have probs with the new bike the dealer was helpful and followed up to check everything was now ok. So fair enough, but I have heard some terrible stories about other dealers and importers, that may or may not be true.

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There is an esier fix for it than having to drill holes but it can be time consuming as it is trial and error i did it on my 03 rev3 and it was to bend the plate that the floats push on to close the needle very slightly refit and test but if you go to far you know about it cos it starves the bike of fuel as it closes to early so just bend it back slightly.

but dont try it unless you are sure of what you are doing!

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The 5th pic shows the drilling in a different place to where JLI's did mine 2 or 3 years ago. Just above the new hole (arrowed) is a raised/flat nipple with an indent preformed into it - this is where mine was drilled out.

Mine too. :icon_rendeer:

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