I put the cam timing right in September Kenny. The bikes got more power now. I need to get it on the Dyno again as it is with the Y piece and then again with a standard collector box.
Y Pieces
- Thread starter Rob Farmer
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Your bike is a bigger project that Vincents !!!
judge
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Now if Judge had got his act together and posted his dyno run with the collector box fitted we would have something to compare them to
Not so easy now I don't own the bike, it along with all the paperwork now resides with the new owner of the bike in Dublin.
judge
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But you don't need my one cos this will be very similar; R100GS with collector box with Cray Stage 1 Road Tune modifications.
ROB not sadBeing a sad git. I've just transposed all the data to an excel spreadsheet. Quite interesting when the data is standardised.
BamBams bike is throwing out quite a bit more power lower down than the standard bike but runs out of steam. Mine was just shagged
Obi-Wan Kenobi to Airhead ownersI need that power at the bottom end as i'm fat
onyack and at speed it tankslaps like a gooden
next time lilith rides it must remind her as I neglected to last time
judge
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Being a sad git. I've just transposed all the data to an excel spreadsheet. Quite interesting when the data is standardised.
BamBams bike is throwing out quite a bit more power lower down than the standard bike but runs out of steam. Mine was just shagged
Errr squeeze me but if bumpmuncher's bike is the one from the dyno then it is far from a standard R100GS
Errr squeeze me but if bumpmuncher's bike is the one from the dyno then it is far from a standard R100GS
Bumpmuchers graph has two plots on it. One from the standard 100GS the other from a stage 1 cray bike. I only plotted the standard GS figures.
bumpmuncher
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sadly that is not from mineErrr squeeze me but if bumpmuncher's bike is the one from the dyno then it is far from a standard R100GS
, got it from jim with list of mods he does. hopefully get him to do a few bits to the heads when i get the valve guides done 
AliBaba
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BamBams Dyno-reading looks wrong, unless the bike is extremely modified.
The speed-range is 35-135 km/h which transfers to 1380-5300 rpm. Have you seen any other dyno-run for a GS that starts with 1380 rpm? I haven’t…
One explanation might be that third gear is used during the process, this will give an RPM-range 1650-6600 rpm and a curve closer to Bumpmunchers standard engine but with a large dip somewhere around 4000 RPM
The speed-range is 35-135 km/h which transfers to 1380-5300 rpm. Have you seen any other dyno-run for a GS that starts with 1380 rpm? I haven’t…
One explanation might be that third gear is used during the process, this will give an RPM-range 1650-6600 rpm and a curve closer to Bumpmunchers standard engine but with a large dip somewhere around 4000 RPM
You're right Alibaba it stands out a mile
I simply transposed the kph to Mph and then cross referenced my charts rpm to the speed.
Just getting a selection of readings together before we look at it properly.
I simply transposed the kph to Mph and then cross referenced my charts rpm to the speed.
Just getting a selection of readings together before we look at it properly.
I've been back for another session on the Dyno.
Everything on the bike was put back to standard with the exception of the Y Piece.
New jets and needles fitted along with O rings and the tappets and timing were checked.
It's now running 44 BHP instead of the 37 BHP when I got it - A 19% increase in power. It's also got a much better torque curve.
Looking at the graph the mixture drops through the floor around the midrange point, hopefully this will be cured once the needle has been dropped one notch. I'm running standard main jets (150), the mixture starts to come back in line once the bikes flat out.
So it looks like the Y piece does cause an issue but should be curable by dropping the needle one notch. I'm hoping mine will make more power once the mixtures correct.
The Original
Everything on the bike was put back to standard with the exception of the Y Piece.
New jets and needles fitted along with O rings and the tappets and timing were checked.
It's now running 44 BHP instead of the 37 BHP when I got it - A 19% increase in power. It's also got a much better torque curve.
Looking at the graph the mixture drops through the floor around the midrange point, hopefully this will be cured once the needle has been dropped one notch. I'm running standard main jets (150), the mixture starts to come back in line once the bikes flat out.
So it looks like the Y piece does cause an issue but should be curable by dropping the needle one notch. I'm hoping mine will make more power once the mixtures correct.
The Original
Well thats it! made a huge difference to my bike. much cleaner on the midrange. If you have a Y piece fitted drop the needle one notch
I've been back for another session on the Dyno.
Everything on the bike was put back to standard with the exception of the Y Piece.
New jets and needles fitted along with O rings and the tappets and timing were checked.
It's now running 44 BHP instead of the 37 BHP when I got it - A 19% increase in power. It's also got a much better torque curve.
Looking at the graph the mixture drops through the floor around the midrange point, hopefully this will be cured once the needle has been dropped one notch. I'm running standard main jets (150), the mixture starts to come back in line once the bikes flat out.
So it looks like the Y piece does cause an issue but should be curable by dropping the needle one notch. I'm hoping mine will make more power once the mixtures correct.
The Original
Wow! There's a lot of variation between the bikes. I'm especially surprised at the HPN figures. It really makes you wonder just how much (or little) research/tuning work the after market suppliers really do.
I'm not entirely sure what stage of tune Jill's 100 has but it has been done by Jim Cray. The exhaust is a full stainless system with 'Y' piece but the headers have a balance pipe. It's also twin plugged and gas flowed.
I've not ridden any other Airhead GS's for comparison but I'm quite pleased with it's performance when compared to the 1200 and the 650GS's we also have.
I was however not expecting it to be very much different from the 650 to be honest as there's only 10 BHP between them on paper, and it seems quite close power-wise, though the 650 will out perform the 100 in the handling stakes every time with both bikes in their standard set-up.
Val.
SJRoome
Registered user
Dropping needle
Hi
I would like to try changing the needle setting as I also have a R100GS with a Y piece and completely standard carbs (not that I need really need any more performance). However I am puzzled by your reference to dropping the needle. Wouldn't this put the needle further into the needle jet and hence weaken the mixture?
Hi
I would like to try changing the needle setting as I also have a R100GS with a Y piece and completely standard carbs (not that I need really need any more performance). However I am puzzled by your reference to dropping the needle. Wouldn't this put the needle further into the needle jet and hence weaken the mixture?
That's exactly what in needs. My bike is completely standard apart from the Y piece and hasn't been running too well. The dyno run today showed that the mixture was very rich across the midrange section of the rev range controlled by the needle. I've dropped the needle down one notch to the second notch from the top. The difference is amazing. I'm not chasing horsepower but do want the bike running as well as it possibly can.
I know it sounds a strange thing to do but the Y piece is causing the mixture to run rich to the extent that it's strangling the bike. dropping the needle means the bikes burning more efficiently so runs smoother and revs cleanly. It's not going to cost you anything to try. You will be surprised the difference it makes and you will use less fuel.
I couldn't justify spending another £30 for a dyno run after I'd dropped the needles. It would have been nice to see what the improvement looked like.
I know it sounds a strange thing to do but the Y piece is causing the mixture to run rich to the extent that it's strangling the bike. dropping the needle means the bikes burning more efficiently so runs smoother and revs cleanly. It's not going to cost you anything to try. You will be surprised the difference it makes and you will use less fuel.
I couldn't justify spending another £30 for a dyno run after I'd dropped the needles. It would have been nice to see what the improvement looked like.
SJRoome
Registered user
Y piece
Hi Rob
Thanks for your note. It was your comment that "the mixture drops through the floor" that fooled me. I should have looked more closely at the graphs.
I fitted my R100GS with a Keihan system with a Y pipe 5 or so years ago. On my first test run I got popping and banging on the overrun. I notice lots of people on this thread report this. This is due to poor sealing between the components of the exhaust system causing air leaks. I made up some stainless steel gaskets to correct this and immediately had no more problems. The sound was a bit tinny at first but a bit of use cures this.
I have just cleaned and balanced the carbs and fitted new plugs so I plan to try reading the mixture using the method given here http://www.strappe.com/plugs.html
I may then try dropping the needle, but I am concerned about getting too weak at lower revs and overheating the engine and plugs.
Steve
Hi Rob
Thanks for your note. It was your comment that "the mixture drops through the floor" that fooled me. I should have looked more closely at the graphs.
I fitted my R100GS with a Keihan system with a Y pipe 5 or so years ago. On my first test run I got popping and banging on the overrun. I notice lots of people on this thread report this. This is due to poor sealing between the components of the exhaust system causing air leaks. I made up some stainless steel gaskets to correct this and immediately had no more problems. The sound was a bit tinny at first but a bit of use cures this.
I have just cleaned and balanced the carbs and fitted new plugs so I plan to try reading the mixture using the method given here http://www.strappe.com/plugs.html
I may then try dropping the needle, but I am concerned about getting too weak at lower revs and overheating the engine and plugs.
Steve
Val it has a HPN Baja silencer and a KN on a stock engine oh nad theY piece (Stainless, lighter and cheaper than a Collector box!!), set up to get me to Morocco. So I thought it was pretty good for a bolt on.
The problem is getting the air in,it needs to make it perform.
I have a few tricks to try and will let you all know the differace they make on each run.
On the ground it considably quicker than Liliths GS, which is still a suprise to me as Lilith is considerably Lighter. and when she rides mine it flys
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