KR-1S.co.uk Forum

My old race bike had 26j pistons, 35mm carbs, standard exhausts, put out 59bhp on a dynojet dyno, was built by Graham file. Cant realy say how quick it was as I only used it for 3/4 of my first race season, looking back I think I probably had the wrong gearing for brands Indy but still managed a 60 second lap, don't know how this compares to your lap times? It was a bit damp on the Sunday was'nt it

Blue shock waves KR1S which had a Mick Abbey tune and Lomas pipes only pulled 48bhp on a dynapro

headcoats wrote:Blue shock waves KR1S which had a Mick Abbey tune and Lomas pipes only pulled 48bhp on a dynapro

I struggle to understand how you can send an engine away to a tuner and it come back with less power than what it went away with.

I understand that the Bemsee dyno reads a bit low to be honest, but even so, I didn't expect that low. I have a spare set of standard KR1S barrells, KR1S pipes and a set of Gibsons to play with before my next race

Luders wrote:

headcoats wrote:Blue shock waves KR1S which had a Mick Abbey tune and Lomas pipes only pulled 48bhp on a dynapro

I struggle to understand how you can send an engine away to a tuner and it come back with less power than what it went away with.

I wouldn't have expected that either... But in defense of Mick Abbey he has tuned one of my AR head and barrels (std 123cc bore and stroke) and it kicks out 30bhp with good torque through the range. This was confirmed on a dynapro. Main jet went up from 135 to 210 on vm26 carb. So no complaints from me.

I'm not slating anyone but that was the facts

Ian Booms Mickey Abbey tuned LC with Kenny TSA pipes and Zeeltronic made 71 BHP on same dyno,however same tune with Allpeeds made 49BHP and about 54 BHP with a powervalve box mod

headcoats wrote:Blue shock waves KR1S which had a Mick Abbey tune and Lomas pipes only pulled 48bhp on a dynapro

I found Lomas pipes on stock porting lost you a hp or two at the top end but you did gain midrange - compared with stock KR-1S pipes (might be the reason for 50hp stock dropping to 48hp). On my engines I have found that raising the exhaust port and KIPS port 1mm helped the Lomas pipes improve or match top end power compared with stock pipes whilst keeping the mid range boost. Lomas pipes are the only pipes I have tested that on a dyno showed an improvement over stock pipes. All other pipes either underperformed everywhere or gave a midrange boost but lost top end. I need to qualify that by saying they were only ever tested as bolt on power improvements (or not) and not as part of any calculated programme of improvement.

If a KR makes less power after tuning than a stock bike then something is not right. I have posted what I do and I know it works. Having said that I know others have tried and had poor results but I am not sure why?

This picture shows what you can achieve (posted it many times before but it is a good reference)
Pink is full on motor 35mm carbs, Vforce 3, Lomas pipes ported barrels, flowed cases the works but still on stock ignition. Anybody with a bit of time and care and the right parts should be able to match this.
Green is pretty much the same motor but on Stock pipes so you can see the boost Lomas pipes gave me.
Blue is the Bonneville bike before it went to America - basically flowed cases matched barrels and head squished. Everything else standard.
Red is the Bonneville bike as I bought it completely stock.



In tuning I avoid making the main exhaust port wider and I also keep it lower than the KIPS. I have seen engines from other tuners that make the KIPS and main port the same height. As I only ever saw those engines as they were apart following a seizure I would avoid that method of tuning.

I go with what I have learnt from racing a KR for the last 13 years. I know what I do works and is reliable

If you are racing and are having problems I am happy to take a look at an engine. Forgot to say I will only look at it if it is clean enough to eat your breakfast off - I can't be doing with wading my way through dirty grease and grime.

Hi Mark,
would be great if you could look at my engine if I get stuck and its going no-where if Bob Farnham can't/won't sort it out, but thats all a bit speculative at the moment. Don't worry - my engines are always clean

Mark, I suspect anyone that hasn't got these kind of power results out of the KR motor, have deviated from your advice in some way.

scooble wrote:Hi Mark,
would be great if you could look at my engine if I get stuck and its going no-where if Bob Farnham can't/won't sort it out, but thats all a bit speculative at the moment. Don't worry - my engines are always clean

See how you get on - I am hoping to be at the September Brands meeting so if you are still having problems we can have a chat. The Dynopro dynos are pretty good. I ran my KR on Mark Dent's portable unit at Snetterton and then then on James' (Krazy Katt) Dynopro and got the same result within a 1/4 of a hp.

Dyno curve looks like the KIPS not closing.

Closing or opening? and which dyno curve.....

I do know for sure that the powervalves were opening as I could see them. Before my last dyno run, I started the engine, revved it to 8k and quickly shut it off, removed the pipes and looked up the ports. All P/V's looked to be open. The outer ones where about 95% open though.

Its interesting that both mine and marks curve show the same dip and recovery between 8k and 8.5k - its just that mine starts off low and doesn't get any better.
I spoke to Bob yesterday and he said he couldn't find any evidence that the crank seals were blowing

I still suspect it's what's been done to the barrels.

you could be right. I can't really compare before with after, as the only things are the same are the spannies and the cylinders/head (and its those that have been tuned).
I started from a new set of cases which I did a small amount of flowing on (basicly taking off the sharp edges etc), installed new stator, pickup and flywheel.
Both Mark Dent and Bob think it could be the pipes, but on my other set of cases with a near stock engine (except squish), I remember I was almost keeping up with Kevs bike (TheElf) down Cadwell straight and it was good enoug to keep up everywhere else (still using the same Nikon spannies). I'm due to pick up the engine this weekend and will set about building it back up and get it tested on a local (Dynapro) dyno.
I've now got a new KR1S gearbox for the other engine, but I think I'll have a go at flowing that too.
Incidenally, does anyone know what the average pressure should be on KR1S engine, I've got a compression tester and want to check it out.