Hi All
I've got a pair of Jolly Moto pipes and was wondering if the end cans are supposed to have a suporting bracket like the std ones as they clamp on

nice choice Mr Howl !
i've slapped some jollies on myself. there aren't supporting brackets supplied as standard. i've been running them without with no problems. they do move about a little but i calmed this down using a large hose jubliee clip wrapped around the two chambers near the headers.

cheers,

Dave.

Cheers Dave . I'll leave them without then . I didn't think they did as there was no marks on them .

i'd be interested to hear how your jetting is effected. i had chance to do a plug chop this weekend and the plugs looked perfect with no change to the jetting. i can't see any obvious signs that it's been tinkered with but haven't had the carbs off yet.
it does feel a bit lean up the top end of the counter. feels like it should be making more power but maybe that's what an mc28 does feel like !?!?!?

Dave.

It's no real shock to find if you've not changed the inlet side of things that nothing much has changed, swapping from the Tyga pipes to o.e. (for a quiet trackday) did little to my '28, closing the airbox off (I still got black flagged for noise) made it mega rich, I could probably have gone down 3 or 4 sizes quite easily.
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good point Mr Fontyyy. i suppose if there's no more air than before being dragged in then there's a limit to how much things can change.
what would you say about my topend power ? all the way up to 9k or so it seems to be making great progress...from then on it seems to peter out and becomes a little disappointing if i'm honest. it still pulls but lacks punch of lower down.

cheers.

I've never ridden a 28 in any form on the std card and flywheel, with or without the airbox modded but it's no real shock to hear it's pretty underwhelming. All you've done is the pipes?

My racebike has the 030 card, Tyga pipes and open carbs, freshly ringed it makes between 62 and 63 bhp and pulls really nicely right round. It's a good match for any truely stock barreled mc18/mc21 (Andy's optimized bike does not count).
With the stock (but derestricted) pipes it lacks a tad of top end zip (past 10 k or so), 56-57 bhp? Covering the airbox holes up kills it stone dead though it was silly rich, low 50's at the most, 10,000 rpm in 5th up Schwantz Curve was all it would pull.

My roadbike isn't really that much of a '28 at all. It's an entire 21 motor inc. carbs and modded airbox dropped out of a 21R and put into my '28.
The pipes are stock '28 with the washers ground out and it runs stock 21 cans. It'd be around 60bhp on a PGM3, it's not making that but it goes quite nicely really, I was pleasantly surprised.

I've also ridden Leigh's roadbike, stock mc28 engine, mc21 flywheel, JHA pipes, stock airbox, makes 54bhp (I think) and that makes nice progress but I found it a little disappointing, it just doesn't rip onto the pipe like, well, like a 2 stroke should I guess.

Looking on the Tyga site there is a graph of a '28 with just their pipes on (vs stock restricted) which as you say doesn't really zip at the top, fitting a '21 flywheel helps quite a bit - graph here and modding the airbox graph here gives another small increase, but nothing like what you get with a '21 just by modding the airbox (graph here) which probably shows the real restriction is still in the PGM4.

The problem with the '28 is nothing is designed for power, low geared, more spaced ratio gear box, lower ported barrels (anyone know how much power this looses? It's not much anyway, mine made 60.x on an open airbox - no lid - and both '28 barrels), restricted pipes, restricted airbox and worst of all, restricted PGM.
Leigh has back to backed mc21 and mc28 flywheels I believe but to show how far from a HRC card the mc21 flywheel is Tom found 11 bhp on his 300 swapping from PGM4, stock card and mc21 flywheel to PGM4, 030 card and mc28 flywheel. 11 bhp!!

I don't know what to tell you really, if I were you I'd take the airbox lid off (means you don't take a drill to your spotless lid, wire the filter in place), go up a couple of jet sizes and see if that makes a difference (obviously chop it, go down again if it's rich etc), then I'd get hold of an MC21 flywheel, a flywheel puller and try that.
Without the card (or a PGM2 or 3 instead) or internal engine mods that's about it.
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cheers Fontyyy ! the effort you've put into that reply is much appreciated !
it reads as total sense with regards to what i'm feeling with my 28. all i've done is the pipes. maybe i'll try the flywheel now i know it's nothing unusual to be underwhelmed by the top end. i'm not after stupid power but a bit more urgency up top would be nice. i just love the 28 and wanna try and keep it as standard as possible engine wise.

thanks again !

Dave.

Mine has Tyga pipes and a chopped airbox lid. Choping the lid made a differents to top end power on mine and it felt a bit more responsive. The standard lid only has peashooter holes that look to be smaller than the rest of the intake.

Has anyone checked to see what the powervalves are doing with the standard card, might be restricting power in the high gears by not fully opening them.

I advanced my 28 flywheel 2 degree's with a stepped woodruff key. This one is the protype thats 5 degree's.

Dave,did you have to make up little brackets to bolt the pipie to the frame as the holes are 35mm out . Not so bleeding Jolly pipes !

hehe ! no mate, i think you'll find that the pipe headers will push into the collars a little further with some persuasion. they're a tight fit but that will get you in line with the frame mounts. use some lube if you have to !

Dave.

Do you use the std gaskets or silicone the exhaust flange straight on to the barrel as 35mm seems miles off.

i used a set of copper gaskets that came with the pipes initially. they were a lot thinner than the originals. one of them got a bit mashed during the install so didn't seal properly. i've since gone back to the originals. the fit is a bit tighter but not too tight that i can't line up to the frame.

would your mounts line up with no gaskets ?

Oh well, I had a go at fitting the pipes today with mixed results. The pipes do need a bracket ,but no problem so they were made up. Next problem is my bike is jacked up a bit with the rear F3 linkage ,so the pipe hits the swing arm on the right hand side .At the moment it sticks out at an odd angle, just to try them.
I have two choices ,put the std link back to raise the swing arm or bash the pipe. Replace the link then !
They do sound good even just warming the bike up outside the garage.


Last edited by howl on Mon Apr 07, 2008 6:06 pm; edited 1 time in total

give and take to find a happy compromise my nsr loving friend !
lets have some pics !!!

Dave.