ON A 250 JUG. We have to remember that for even larger performance increase with a larger diameter carb the 351 is needed. If you test with the big bore and find a small difference I will be convinced. Going from cv to tm on my big bore was a massive difference in wide open acceleration.

 

Are you gonna do a big bore in the future Richard??

 

Yes he is Matty.. He has a 330 kit waiting installation..

 

I'd expect the bigger bores to respond very well to the bigger carb..

My WOT jetting turned out to still be perfect, so there's no power left on the table. The mid range was lean so I richened that up half a notch. It may take another 1/2 notch to get it right; I'll check it again later today.

I'd say this little experiment has gone about as far as it can. All things considered, it's still probably easiest to just bolt on the TM36-68 and not have to fabricate or adapt anything. Getting the accelerator pump to boot.

 

Ahh, I guess your "1/2 notch" refers to the needle setting? I'm not aware of 1/2 notches on a needle..
Assuming that you are richening the mid range with the needle position, your acceleration should be enhanced in that range. My bikes' needle at WOT - from my last dyno test - seems to come in to play relatively strongly from about 5250-7250..

It'd be nice to have run data on a fully optimized CVK with the modded boot.. Why would we buy a TM-36 for our stock bores if a optimized CVK with a boot mod does the same thing..?

 

I use .020 washers to shim the needle half a notch when that's all it needs. I just took a shim out and richened to the middle notch. The a/f at part throttle positions is better now, but could probably stand another half notch on the needle.

The "why" IMO is because there's a fair amount of adapting to be done to achieve a effective/well done modded boot, especially if it's to be suitable for messy off-road situations.

I'm going to put the 36mm back on in the next few days since it appears to marginally quicker and has the AP. Probably trying the modded boot with it just to see if it affects the 36's performance.

Since I've tried all the easy mods now, the next level will be pulling the engine so I can open up the intake port a little to match the stock intake which has been opened up 1mm all the way around. But I'll wait awhile and just enjoy riding the bike before I do that.

 

I will to tell you sticking that filter out there is not good for extremely dusty conditions or, obviously, water crossings that may either saturate the K&N or actually submerge it. K&Ns aren't all that good in dust, they make a foam sock to cover them for those conditions. Virtually all off roaders do the foam with air boxes for those reasons.

I don't know what is available from K&N, but something with an offset would do the job if possible, especially if you consider doing the following...

One thing flat trackers do, and could be a consideration since your use is primarily road, is to go with a low pipe. Yoshimura did one for their Supermoto DRz400 that Kevin Schwantz raced. The more gradual bends allow better flow for better power. Thus the reason the flat trackers do it. Only negative for some bikes is if the silencer/muffler reduces road clearance as it did on my first SR500, but with either the SM or dual sport this wouldn't be an issue on the road.

Using a low pipe freeing up space up by the carb makes for some interesting air intake possibilities... but don't look to me for that stuff - I'm going off road.

 

The KTM Freeride uses a downpipe tucked in between the frame rails

I'm not going to stick with this modified boot anyway, unless perhaps it makes the 36mm carb yield more performance.

 

I'd have been remiss if I didn't, so I tried a run just now with the stock boot..


The bike felt good, nice big wheelie on the 1-2 shift and a 5.31 elapsed time.

So the boot mod at best appears to only gain .09 sec over the stock boot in this experiment/and .09 sec slower than the 36mm.

The 36mm carb is .19sec quicker than the CVK with stock boot.


That's over a short course; over a 1/4 mile the performance edge the 36mm has might even be larger than .19 sec, and the modded boot may be more than .09 quicker than the stock boot in a 1/4 mile comparo

 

One more test just to see what happened:

A 5.16 with the 36mm and boot mod just now.

If it helped the CVK it isn't helping the 36mm