Why do oversized PV covers do what they do?

[jgas]

I'm bringing this thread back cause I want to. Gotta put in my .10. My .2 is worth more in my not so humble opinion.

Manufacturers have to compromise. No choice but to try and make a bike that is suitable for as many as possible. No doubt GG has current and former racers test their bikes before production as all companies do. No two people or even pro level testers like the same things on a bike. I've ridden pro racers bikes that I loved, and that I hated. More that I hated! I'm old, fat, not lazy but not really in shape due to 27 surgeries with 3 more lined up. I ain't no pro rider. Never was. Sure ain't now!

I like 2 strokes, but am usually faster on 4 strokes. Not really sure why unless it's mainly that I like engine braking, and they tire me out less. Many riders are tired out less from 2 strokes! We're all different.

Recently I had a KTM 250 EXC. I added an SX head and piston, SX CDI box, and used the red powervalve spring. I did all that because some knowledgeable guys on ktmtalk said to try it. I was convinced they were nuts! My idea was that it would make the bike hard to ride, overpowered, violent, etc. Which it did do. In 1st gear only. It all added up to so much smooth torque down low I could use 2nd gear up for almost all situations. Eventually I went up 1 tooth on the countershaft sprocket, which made 1st gear perfect for the gnarly stuff, helped top end when cruising on a dirt road, and I usually stayed 2-3 gears high when at speed and slipped the clutch a little when I wanted more power. It was much easier to ride, got much better fuel mileage, and was just more fun. A buddy of mine who was faster than me hated my mods, but he prefers a hard midrange hit and overrev. He is also 18 yrs younger and far more talented.

Ok, my .10 is that more torque is a good thing. "4 stroke" like power is a good thing. For me, anyway. Probably not for Russell Bobbitt. But ask him when he's nearer 50 and has had 27 surgeries? If I can find one of these covers, I'll try it and add my .2 You already got my.10

[swazi_matt]

Ok figured i would post this here rather than start a new thread.

I ordered one of Elvis74's 15mm powervalve cover spacers and fitted it to my 2010 ec300. I was a bit worried as i had heard that the spacer has a much more noticable effect on the 250 than the 300 but thought i would give it a try anyway.

The product is very nicely made wit the external finish water cut and looking almost identical to the cylinder head, so not a bling item but nice and discrete. along with the spacer you get two gaskets and also a set of longer allen head screws. with regards to the product, the only chang i may make is to add some washers to the screws, but there may be a reason why Elvis left these out. about a 5 minute mod to remove cover add spacer and gaskets and bolt up

Anyway went for a short ride on saturday with it and 99% of the time i was in first and second gear so ideal to test the effects low down - result i found i was running a gear higher that i thought i was (i am one of those riders that never know what gear i am in only that i need to go up or down) and was often surprised to find i was in second and not first.
definitely chuggs better and also it sounds a bit nicer i think, has that bigbore cr500 kind of tone to the engine

in the last 300m of the ride i got chased by a dog and when you wind that throttle from chug it seems to explode nicely and start moooooving out!

It is not a huge difference (slightly more noticable than the difference the map switch makes), but does add on the bottom and does not change the nice characteristics of the

so all in all i am happy with the mod and money well spent

[Jakobi]

Good read Matt. I actually had Dave machine me up 3 spacers each 8mm thick. Once I get the jetting dialled in on the 250 I plan on then running from stock, 8mm, 16mm, and finally 24mm to see how the changes effect the power delivery. I've got a few spare gaskets here but will probably just use some liquid gasket to seal them up and have some spare bolts ready to rock.

I have been a bit turned off since Bailey posted that it softens the response as I really enjoy the crisp snappy delivery too.

[lonetree]

i put on of the mainjet ones on my 250, and from what i've ridden it, seems really good.
mine will happily pull itself and me along on idle in 2nd, and not stall. I have had a spacer made up as well but it would make the overall chamber about 50mm deep but i might give it a try for a laugh.
The main jet one is about 25mm extension on stock...

[GMP]

I've been running these for years since the first Tafta covers back in '00. They help with grunt on the very bottom, reducing the stall speed. Its a subtle difference though. This is good on the 250 ridden slow in technical rock trail with a lighter flywheel, less so on the 300. Also pipe dependent, but now most if not all of the pipes seem pretty balanced. Back in the early days the old FMF Gnarly pipes were true bottom end pipes, and the cover was somewhat usless especially on a 300. I don't think it softens throttle response at all.

[Elvis74]

hey matt, nice report!
Some of my friends noticed that they had to change the air screw adjustment and some also changed the carburator setting.
I loved to ride with these plates, too bad that there is no possibility to put it on the 144cc I have right now.

[swazi_matt]

Originally Posted by Elvis74

hey matt, nice report!
Some of my friends noticed that they had to change the air screw adjustment and some also changed the carburator setting.
I loved to ride with these plates, too bad that there is no possibility to put it on the 144cc I have right now.

It does seem to be running a little bit leaner but I was on the rich side so seems fine now

[swazi_matt]

Ok did some serious rock climbs this weekend, the type where you are happy to get 5m before you stop/almost flip, and i really noticed the added torque. It seems to be much easier to put the power to the ground and with less stress to the clutch.

My riding buddy even asked me if i had fitted a rekluse to the bike, he noticed it and was not riding it, so not a placebo effect!

I will be interested to hear what you guys feel when fitting your bigger PV spacers, but to be honest i do not think i would need any more than what i have now

[Jakobi]

How much extra did you bring yours out Matt? Did you end up jetting differently for it? I've still been too lazy to do any testing on the 250. I might have to drop one of the 8mm spacers on it tomorrow and go for a quick ride.

[swazi_matt]

i put in one of elvis74's 15mm spacers. I did not change the jetting, but think it is running a little leaner than it was.

I have heard that the gains are more noticeable on the 250

All i want to do now is go out and ride the most gnarley rocks out there!

PS please get back on your ttx suspended bike soon ... it is almost satanic having it just stand there!