Clubman on GT186 - Ex Box?

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Hughieboy
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Thu Nov 21, 2019 10:46 pm

Or if it’s at lower revs with open throttle under load, could it be fuel starvation/under jetting? That feels similar to a slow heat seizure when it happens...

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coaster
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Fri Nov 22, 2019 2:15 pm

Scooterdude wrote:
Thu Nov 21, 2019 8:37 pm
coaster wrote:
Thu Nov 21, 2019 11:27 am
I've been running a BGM Mk3 Clubman on my GT240 for about 4 years now having had mostly expantions on other enginers (Avanti, TS1, Mugello) and can say that it runs very well through the gears with a smooth flat power curve and tops out about 75mph. Ive never had any over heating problems with it but this year fitted an EGT and was amazed to see temps between 700-800 degrees :o AS the CHT was reading around 200 degrees atbthe time Im putting it down to the previously mentioned 'gassing' effect.
Jesus wept!! Cht 200 degrees c? Egt 800 with temperatures like that you’re sure to kill it to death in a very short space of time. Can you not get someone to replace the stinger with something around 30mm id? Definitely worth it.
oops that was a typo, the CHT tops out at 120 degrees Centigrade. I dont know why the egt reads so high, the engine has taken me to Italy, Spain and other lengthy trips without issue but I recently fitted a Scootronics Gamma Speedo so decided to fit the EGT probe and was suprised at the high reading, I am confident that it isnt over heating in the comustion chamber as I have held it at between 60-70mph for 50 plus miles at a time loaded up with luggage.

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Scoot
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Tue Nov 26, 2019 8:16 pm

Hughieboy wrote:I’m currently running a TSR Evo on my GT186, 30mm phbh and no filter, happy enough with the performance but the fit is terrible, it hangs down too low and despite repacking the silencer is annoyingly loud...

I’m wondering about buying a Clubman - like the look of the Gori GP50 but am worried about fitment and finish (60/110 crank with packer) then there’s the BGM V4 and the Avanti Ex Box which both appear more adjustable.

I’m leaning toward the Ex Box purely because of the description given on the Supertune website but having not run a Clubman before I don’t know what to expect performance wise. I expect it would be quieter though..

Can anyone with experience of these pipes on a GT186 comment? I guess it would affect the power output taking off the expansion but would it knock the stuffing out of it?

Be grateful for any opinions.
My GT186 with a super tourer was 17hp. With a BGM4, 14hp. Much nicer ride with the BGM.


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Muttley McLadd
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Tue Nov 26, 2019 10:42 pm

If you can find one, you could do worse than an RS Clubman on a GT186. Mine had 17hp and pulled 4.6 gearing. No racing snake off the line or TS1 chaser, but could sit flat out on the motorway, well above 70mph.
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Hughieboy
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Thu Nov 28, 2019 11:20 pm

Thanks for the info fellas. So, decent Clubman means less horsepower and so less lively but more bottom end and so more grunt and can pull taller gearing. Meaning higher top/cruising speed at lower revs. Is that right? I’ve just been struggling to get my head around the ‘less is more’ horsepower thing, but I’m getting there with it! Horsepower is not everything, right?

It would be great to have decent grunty overtaking performance when needed with a good cruising speed

Adam_Winstone
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Fri Nov 29, 2019 5:40 pm

^... the fact that you've grasped enough of the concept to be querying it is a good sign, and I mean that genuinely.

More is more... but not at the cost of having less at other points along the graph's bottom axis. If you could get more across the whole graph then you're doing something very right. However, typically, this 'more everywhere' scenario tend to be the result of a complete change of specification or a straight capacity increase. Bore a 150 to 175, or 200 to 225, and you'll probably be in the 'more everywhere' scenario but tuning (rather than a change of kit) will typically give more power across a certain rev range (powerband) at the cost of losing power at other revs. The saying, "You never get something for nothing.", commonly rings true for tuning... but not always.

Many productions are designed to have very wide safety margins and may have been designed to cover 50,000 miles at 50mph, whereas a sporty rider may well be quite happy doing higher revs for 30,000 rebuild intervals at 65mph. As such, you can often do mild tuning for a reasonable increase in performance, for no loss of reliability... just a more regular maintenance schedule.

The issue with tuning, which where your question comes in, is that it's a sliding scale of what you want from it in terms of performance vs how you like to ride, how fast you want to go, how short you want that maintenance spacing to be, cost (!), etc. BUT you need to go back to considering the 'nothing for nothing' quandary and this is where the issue of 'how far can I go?' comes into it.

Talk to most people that have gone down the route of Lambretta tuning and they'll tell similar tales of tuning barrels and or fitting components that make their bikes go faster by revving harder on the same gear ratio speed = RPM x gear ratio .... so if your bike now revs higher then the bike goes faster. HOORAY!.... but....

[NB: You then need to ensure that your ignition timing is appropriate too keep your faster spinning motor cool, a likely increase in jetting, etc.]

The above increase makes you think, "Wow, I like this and want more of it!", but typically the next increase of tuning or higher BHP/higher RPM components does something that you were not really expecting... 1st - Wow that bites, 2nd - feeling it, 3rd - Flip me, this bike is producing much more power and really motoring, 4th - Um, come on 4th, where did the power go?! Holding it open, not really doing much, certainly not like the other gears... head scratching?.... drop it back into 3rd and take off like a scalded cat! This is when you start to get the nothing for nothing concept of tuning, however, a change to a lower 4th ratio and it now takes off through the entire rev range, reaches it in 4th and can stay there under a broader range of driving conditions. The motor is now in the state of tune where it is producing much more power (BHP) but across a narrower rev range... which actually equates to it normally doing less BHP outside that powerband. This can be lots of fun but can get tiring as you can find yourself out of the power as much as you are in the power, and going from 1up to 2up can then put you back out of the power and struggling to chase said powerband.

A solution to the above stage of tune is to introduce a method of increasing the width of the powerband again (e.g. advance/retard ignition timing, power valves, EVO exhaust powervalve, etc.) or something that makes chasing that powerband easier (e.g. close ratio gearbox or close ratio 5-speed box). You should now find that you're still doing high revs for high performance / speed, without having to chase the powerband too much. Indeed, this situation is the basis of much of today's Lambretta/Vespa tuning and can be used for most fast applications, whether it be around town or on the open road... but do note that your maintenance schedule is a factor, as is cost of upgrading components to handle this increase of power.

NB: By this stage your 20+ BHP TS1 225 with revvy expansion is now having to run the same 5.2:1 final ratio as the 6BHP standard LI150, although one is doing 50 and the other 80mph! Your trade off has been BHP/speed for increased revs.

The story doesn't end there though as now that you've reclaimed much of the 'dead zone' (out of the powerband) it is VERY tempting to look to increase the power again, even if it makes that power band a little narrower or higher up your now increased rev range. For BHP figures and pub talk it is frequently found that this is the step that takes it all a bit too far, with your bike having a throttle like an ON/OFF switch, where you're out of the power, then the front wheel lifts as it come on the power, then needs changing up as you come drop out of the power again, which is extremely demanding on components and makes the bike fine for around town thrashing but less fun on the road. Also note that some of the race bikes / sprint bikes out there change their pistons for every race/sprint meeting!!!! ... not something that you want for a road bike.

Frequently, the conclusion for many that go down this route is that there needs to be some balance, not taking things too far. This point will vary depending on intended use, riding style and budget. It is quite normal to find that people who have gone through this process end up with a road/tuning bike that has a good balance of a little less peak BHP that operates across a wider rev range, allowing you to stay in the powerband under most conditions, without having to rev the hell out of the motor... this is the typical 'touring tune' that many speak of (do note that many proclaimed 'touring tunes' are far from what I would consider to be a touring tune!). The good news is that taking a couple of steps back down the tuning progression allows you to be able to fit lesser components (e.g. clutch, ignition modules, etc.) that will happily cope with the more sedate power delivery and the wider powerband allows you to start raising (lower number) the final gear ratio again, no longer having to wring the motor's neck to perform... and remembering the equation of Speed = RPM x gear ratio... you can find that your motor will pull the same top speed but at lower RPM on your now longer gearing.

Balance, it's all about a balance of power vs operating range. You can have as much BHP as you could wish for but that doesn't make it a 'better' ride. Indeed, a pal of mine recent went to a respected dealer's with the intention of buying their 30+ BHP demonstrator... but telling me what he was intending, I told him to take it for a good test ride around town and on the open road. He came back to me with the news that he'd not bought it as it was virtually unrideable around town, to the point of being dangerous power delivery, but great on the open road at high speed and high revs, although he doubted how long the motor would last before it went BANG!

Just be careful and know what you're getting into if you start chasing horses.

Adam_Winstone
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Fri Nov 29, 2019 7:03 pm

^... soz, how easily I get off topic!!!

Apply the above to the Ex Box and it'll take you somewhere between the standard spec and the upper range of BHP return (realms of expansions). I've experience of this pipe and it fits in nicely between where other clubmans hit a rev limit and those that deafen you and/or p1$$ off the neighbours. As such, the increased rev range allows this to be used on some kits, where others strangle the revs, but isn't suited to the very highest tuned kits now out on the market, where an expansion is really the only viable option if you wan to reach the higher revs that those kits perform at.

Hughieboy
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Fri Nov 29, 2019 8:04 pm

Thanks Adam,

To be honest, although I like the ‘whoosh’ it has with the TSR Evo, I don’t like riding it at high revs for prolonged amounts of time. Even though it’s all been rebuilt, I still consider it an old bike and dont want to thrash the knackers off it everywhere. Combined with the noise and the poor fit on a S2 due to panel width issues I guess I have a hope that something like the Ex Box would be quieter, fit better and might allow me to raise the gearing a bit more - currently 16/46 with Pacemaker gears and 60/110 crank - and give me a lower rev highish cruising speed but hopefully not at the expense of losing losing all of its poke through the gears. Don’t mind losing some of the powerband ‘snap’ but would still like to progress quickly when accelerating.

This is where I think I may have been getting hung up on bhp. From what you and others have explained, although the expansion may well hit higher power briefly somewhere in the mid to upper range, for general pull and mile munching it doesn’t matter so much. The TSR does tail off fairly quickly after about 6500 - 7000 revs anyway and I don’t really want to rev much higher than that for any length of time. I think Richard Taylor recommends the Fran Race for the best all round performance but I don’t really want another loud expansion that scrapes on sleeping policemen.... :?

If I’ve got this right, maybe I should just bite the bullet and try one out..

Adam_Winstone
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Fri Nov 29, 2019 9:15 pm

I've no experience of the TSR but TBH that rev range is quite normal, even low compared to what the Fran Race will do... but much of that goes hand in hand with the porting spec of the kit it is used on. Much of this depends on what the individual feels is excessive when out on the open road
I personally found the Fran Race to be best used for higher rev use than I was personally looking for from a tourer... great pipe but the name gives away the concept of it wanting to rev.

Ron's Ex Box is no rev strangler either but does have a good spread of power. I really can't comment about comparison to TSR though.

Likewise, noise level... higher than some more restrictive clubmans but not as loud as some of the other straight through clubmans. NB: Some clubman pipes are loud compared to a well muffled expansion.

Might be worth hearing one?

Hughieboy
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Fri Nov 29, 2019 9:30 pm

Thanks again Adam, really appreciate the thorough explanation given above. Took a couple of reads to absorb it but message received and decided to bite the bullet.

I have just ordered an Ex Box, Christmas cometh early! :D

Looking forward to trying it out now!

Hugh.

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