Mods to my 350LC - want better midrange - Part 1

[muttsnuts]

Ok, so I've decided to bite the bullet and play with my old elsie, she was fully rebuilt last year, rebore, new crank etc, so I know the engine is good, done approx 2000 miles since then, so no worries about running in etc.

I want to improve the midrange, not too bothered about top end, happy with what it will do, so I am looking for pointers, advice, experience etc to save me p*ssing about too much.

My opening gambit is;

1. Skim cylinder head by 1mm
2. Change reeds to fibre ones, V force or Boysen ?
3. Change the carbs to some 31k powerjets that I have
4. Change the air filter from a foam one to something better?
5. Tickling the ports, maybe 2mm off the exhaust ports only
6. Fitting some 6mm reed block spacers
7. Fitting a boost bottle?
8. Fit some high energy coils

I also have some YPVS reed blocks so could mod the barrels so that they fit, but not sure if that is worth doing, so any pointers on that would be great

The bike has small can allspeeds fitted and I don't intend changing them, it is currently running 230 main jets, standard airbox and filter, standard carbs (except larger mains), is 1mm O/S on the pistons, standard porting, standard reed blocks and reeds

I have some spare barrels and heads so can play with them, have seen some interesting changes to squish etc which I might machine into a head and see what it does, however, I don't want to compromise reliability etc, so any mods need to keep this in mind. I also run the autolube and want to keep that, if I have to modify it to deliver more oil I can do that as well.

So there you go, all suggestions, experience, pointers welcome

[artie]

This place does some trick bits as well as your boost bottle Dave,if you have a look around there is a full thread not too long ago all about them
www.nkracing.co.uk/n4.html

[marsbar350]

hi dave looks like youve got most of it covered ;D

[muttsnuts]

Hi Artie, I have all of the parts, so thankfully no great expense this time, I just want to know what others have done really, what works, what doesn't. ABout the only thing I need to buy is the fibre reeds and possibly an air filter, other than that I have everything.

Plus of course I have the machines to do the work, so no farming it out either, just a case of setting up my lathe, milling machine etc to do what I need, oh and not forgetting Mr Dremel !!

[artie]

Here,s the thread mate
rdlccrazy.proboards.com/index.cgi?board=general&action=display&thread=18275

[muttsnuts]

Hi Artie, thanks, that was an interesting read, I forgot to say as well that I am already running YPVS reed block rubbers with the YPVS balance tube, so from what I've read it seems that sticking with that is probably fine and maybe fitting the YPVS cages etc (modding the barrels etc) is the way to go, but I'll wait for others to chime in and give me the benefit of their wisdom - don't see any point in re-inventing the wheel.... ;D

[bare]

1) Measure existing squish.. First
2) Avoid Boysens :-) Vforce are good but Pricey Oem Yama Banshee F'glass reeds are great for midrange and quite cheap to buy
3) Fit Genuine keihin PWKs either new or from a KR1s
4) If you must.. retain the airbox at all costs
5/6/7/8 : Read /learn a Lot... before even thinking on those

IMO Allspeeds are only prettier than Stock Yama pipes.. but produce No more Go
KSA pipes would be a massive upgrade.
G'luck

[muttsnuts]

ok cool, thanks for that, yeah appreciate the allspeeds just look pretty, only way I'd change them is if I could get a really nice set of pipes for similar money as what I'd get for my allspeeds, they are mint and original small cans, so could end up with some better pipes I suppose for similar money

in respect of airbox, basically I am not after sucking loads more air in and from reading various articles, the overall impression seems to be that the standard airbox with a better filter can deliver all the air required unless its top end your after and your motor is tuned to the hilt

Reed spacers, articles suggest this helps the inlet trac and gives a better mix going into the cylinders

PWK carbs, thye do seem to figure in a lot of reading, so might need to source a set of them then

Hadn't thought about the Banshee reed fibres, umm, does Norbo do them?

[midlifecrisisrd]

If you are looking for mid then I would not touch the exhaust port.

As for the airbox I'd keep it especially if you are going to use p/jet carbs as they are a mare without the box. Best to keep it for mid and as bare said pwk's best for mid.

Steve

[Deleted]

i was told to fit kawasaki kx85 carbon reeds as they do the same job but are cheaper by a bloke that works with ron fahron

[muttsnuts]

ok, this is great guys, its all coming together, so now we have the following;

1. Skim head 1mm (check squish of course)
2. Fit PWK carbs - can some one advise which ones, models etc, where I can get them from - possibly new rather than second hand
3. Reeds - seems Banshee or possibly KX85 carbon reeds
4. Keep the standard airbox - yup thats what I want
5. Reed block spacers - jury is out on them
6. Leave the barrels alone
7. Get some KSA pipes if I want real improvements - might do that if someone can give me an idea on cost
8. High energy coils, seems like a good upgrade anyway if I am honest

Anything else chaps?

Also, what I'll do is have a word with my mate who has a rolling road/dyno and see if he will bend his rules and let me put my little thing on it before I do any mods to see what she is doing and then do the mods and then try her again

He normally only does 4 strokes and mad things like turbo/nitros hiyabusa's that kick out 400+bhp, so my misely 35bhp to 40bhp won't exactly challenge is 500bhp dyno !

[cb250g5]

Stop faffing about & put a YPVS engine in it. All the mid range you could want

[muttsnuts]

Jan 22, 2013 21:19:24 GMT 1 cb250g5 said:

Stop faffing about & put a YPVS engine in it. All the mid range you could want

nah, not only is that expensive, I think an LC like mine should have an LC motor in it, if it was a hybrid, then fair enough, but that's not for this bike....

[Deleted]

Jan 22, 2013 21:19:24 GMT 1 cb250g5 said:

Stop faffing about & put a YPVS engine in it. All the mid range you could want

that is just so wrong

[mikee]

dump the head gasket ,lap heads and barrels together , o-ring them helps a lot
set squish at 1mm
make sure both barrels are the same height , squish can be altered with base gaskets
raise the exhaust port 1.5 mm from stock
tidy up the transfers if you like
run stock or 31k carbs , the powerjet ones you have can be a pain to set up
stock airbox and cut a 50x30 hole in the bottom part of the air box beneath the top shock mount
230 or so mains may need bigger pilots too but might not
run your allspeeds , shortening the stinger on them helps (if they have them )
as does shortening the downpipe by 3/4" at the head
set the timing at 1.9/1.8 btdc

raising the exhaust port bang in the middle 3mm higher with a 1/4" round file ,to give a half round indent in the top of the port
and filing a gentle rad on the combustion chamber blending to the squish band opposite the exhaust port so ti is a slight tear drop shape when viewed top down , smooth the power a bit
too

[muttsnuts]

thanks Mike, that's a big help. all of these tips are proving very helpful, once I've gathered all of the info, I'll run mine up on the dyno as is, then do the mods I am going to do and then run on the dyno again and post the results, hopefully it will be positive !

[mikee]

only ever used the arse dyno on these mods over the years
be good to see documented results
a zeeltronic makes a big difference too

this works well on a 250 too with an extra 1mm of the exhaust port

[billy]

Jan 22, 2013 20:46:21 GMT 1 midlifecrisisrd said:

If you are looking for mid then I would not touch the exhaust port.

2nd that. I ported my LC barrels and accidently went up to 28 mm measured from the top of barrel to top of ex-port. Obviously I had to port the other cylinder the same, so it ended up at 28 mm.

I lost a significant ammount of low/midrange. It became rather fun on higher rpms though, my god did it pull when it entered the powerband! But... The downsde is that the powerband got too narrow, and that was rather evident when you drove on 5th and 6th gear. It would slip out of the powerband too easily.

If I would do a port job on an LC again, I'd be much more careful on the ex-ports. I would make them slightly more square shaped, kind of like the YPVS exhausts, and MAAAAYBE raise them a tiny bit, but not much. Maybe 1 mm at most, if even raising them at all. Thing about 2-stroke exhaust ports is that, it's not all about huge air flow - often people seem to forget that you need the exploding mixture to have some time to press the piston downwards before the explosion slips out the exhaust ports. That's the reason why it is common practice to widen the ex-ports rather than raising them. You get more area/flow, but keep the explosion in the combustion chamber for a (compared to a raised port) longer time.

Anyway, I did get a feelable power improvement by slicing the sleeves down at the transfer ports inlets though, I also matched the engine case to the barrels transferports, and it seems to have made a great improvement.
Here's what I did to the bottom of my LC barrels if anyone's interested:





PS: It looks more dramatic than it actually is. I cut off about 8 mm at the front transfer ports and not much at the rear (I pretty much just cleaned it up a little at the rear).

How deep should you go? The answer to that is that you CAN go about 2 mm deeper than I did, but I don't recommend it as going too deep (depending on how you cut it) will/might weaken the sleeve skirt on the inlet side too much (also, I doubt you gain any more power by going deeper anyway).
This is particularly important if you have widened the inlet ports.

So... Put the piston into the barrel and adjust it vertically until the transferports are open about 2-3 mm (or even more if you like), then turn the barrel upside down and you will clearly see how the steel sleeve is an obsticle for air flow. It is very visible on one of the 2nd GIF-image above where the piston is positioned so that the transfer ports are opened 2 mm.

Then simply take away as much of the sleeve as you dare, and bare in mind that you want to keep as much strength on the sleeve skirt as possible, so be careful when cutting around the rear transfer ports inlets.

[bare]

Again: Easiest would be to Buy TSA pipes.
Forgo everything else if you must, you will Still be ahead.
Sell the Alspeeds on to help with the costs.. seriously.
Erm Don't Go cutting up yer barrels as above : waste 'o time :-)
Geez you have the Go Slow motor., Not a Valvie! your choices are 'reduced'
Try 1986 YZ125 oem F'Glass reeds, these can be fitted to the LC reed block after snipping off the 3rd petal

[db8888]

get some old worn out cylinders off ebay and have them bored to fit the dt175 pistons you will have to get the base machined as well I think its 5mm off the base surface leave the ports alone job done...

[muttsnuts]

Hi Guys, thanks for all of the tips, they are all helping in their own way, I've also enquired about some TSA pipes and I am considering it, selling the Allspeeds would be a given, they are in excellent condition, so should go a long way to paying for the tsa pipes, well at least half of the money anyway !

I am at the juncture of leaving the exhaust ports alone, fitting the YPVS reed cages and fibre reeds, fitting some PWK carbs (which I've managed to sort out already), some high energy coils as a stronger spark never goes a miss, skimming the head 1mm, retarding the timing to about 1.8mm BTDC, setting the squish so that its 1mm and looking to fit a better air filter if I can find one

Then seeing what that does compared to what it does right now, I have a spare set of a barrels (thanks Butchers) so I'll get them rebored and have a think about tickling things (maybe), but will see how the above goes.

I am still keen to get more input/feedback, especially on fibre reeds, which ones etc, fitting the YPVS reed cages, fitting a boost bootle or not and any info on a different air filter over the stock foam one

so keep it coming lads, if I can crack this I'd be very happy and I am sure it would help a good number of others on here who must all suffer the dreaded mid-rnage flatness just before the "way-hey" factor kicks in ! ;D ;D

[mikee]

Reed spacers and a bit of milling on the inlet tract are the way to go with valvie reeds
A 10 mm thick spacer and redrilled holes to match the Elsie barrels ,ie drill the holes in the valvie reed cages ,the spacer
negates the need to remove so much metal from the inlet
As for reeds in my experience theres not much between them , boysen dual stage were (bitd) my preffered ones
Tho a mate made some from some c/f sheet he bought for some r/c car chassis , it was .3 mm stuff iirc
And they seemed to work fine so..........

[midlifecrisisrd]

Get your barrels to Mick Abbey. Well known for his good port work and very good price for how much work he does. He did my stroker barrels and I have TSA pipes. I know it's a stroked YPVS so different but what power a standard bike makes flat out mine now does at 7k and peaks under 10k so not a rev hungry monster.

Steve

[muttsnuts]

yeah, reed spacers, will be fitting them. In respect of getting someone else to tweak the barrels etc, I have all of the machinery etc and use to tune race cars for a living, so have plenty of experience with playing with engines, albeit 4 strokes, appreciate Mick and lots of others have a world of experience compared to me on 2 strokes, but I am happy to research and speak to people to canvas opinion, views etc, hence the thread, besides, the sense of satisfaction.....or failure is what I get a buzz from as much as riding my bike.

I will probably go with some TSA pipes, once I've sorted some pennies out, but machining the barrels so the reed blocks fit is an easy job, just time consuming, and I've gone off the idea of playing with the ports as pretty much everything suggests the exhaust ports are plenty good enough and its the inlet side of things that restricts the engine's ability to breath, I am not going for all out top speed or revs, just a more trackedable motor where we spend most of our time on the road.

I am researching a few things at the moment and it's surprising what has been tried to date, pretty much everything I could think of and things I wouldn't have !!

The trick is to get more mid-range, torque at sensible revs without compromising the engines reliability, yeah I know PV' are the way to go really, but some of us don't want to spoil our LC's that way, besides, where's the challenge in swappng the motor !! ;D ;D

keep it coming lads, all good so far.......

[marsbar350]

hi dave
ive got kennys pipes.i purposely went for them,as they give more mid range power on my standard motor.you wouldnt be disappointed ;D

[muttsnuts]

oooo, they are nice, are they stainless as that is what I asked Kenny about making me a set in

[marsbar350]

Jan 25, 2013 12:04:50 GMT 1 muttsnuts said:

oooo, they are nice, are they stainless as that is what I asked Kenny about making me a set in

nah
these are the better mild steel and nickel plated at aggbrigg

[muttsnuts]

ah, Sean has Nickel plated them for you, they look like stainless., which is nice, Nickel is a good metal as well, polishes up well and is pretty resistant to corrosion, umm that's an option then

[muttsnuts]

ok, its been a while since I posted this up and since then I've been going over various things.

Anyway, today I based lined the bike on the dyno and to my surprise its kicking out alot more than I thought and also after some adjustments/fiddling have pretty much sorted out mid range.

So to start with, what's the base line spec of my bike;

1. Standard barrels and head
2. 1mm O/S on pistons
3. YPVS Reed block rubbers and YPVS balance pipe
4. Small can allspeeds
5. 230 mains, standard pilots, standard needles
6. standard airbox and filter
7. Standard reed petals
8. Standard 4L0 01 carbs
9. Timing 2mm BTDC

The bike was baselined with a few initial runs and was kicking out 46BHP, however, it was very flat in the middle rev range - 4k to 6k and would not pull from 4k in top gear very well

After some analysis we lifted the needles up to the maximum position and did some more checks, it was better, but still a little flat around 4k to 5k, after some further work we identified that the needle shape/profile was the problem in respect of throttle position.

Since we couldn't raise the needle any further on the clip, we put some 1mm small washers under the needles to lift them some more.

This time we now have a much smoother power curve and alot less of a hole at around 4k to 5k rev's.

I then fitted the banshee coils I got of Norbo and we did a back to back run, the power curve was identical except it was making 1bhp more throughout the rev range and more importantly all but removed the flat spot.

The end result is that I have 47BHP and can now run the bike in 6th gear at 3K revs, open the throttle wide open and it picks up and revs cleanly through to the redline, with only the smallest hesitation at 5.5K revs, which with some more work on the needle could probably be got rid of.

Out the road the bike is a completely different animal now and so much better to ride, with less of a kick when the power band comes in as its making more power all the time now.

The next steps are to get the KR1S carbs sorted and then do another run with them on, hopefully in a few weeks when I've got all the bits sorted.

So to summarise at the moment, I now have 47BHP at the rear wheel, have Banshee coils fitted, the needle is on maximum position with a futher rise of 1mm and now have a bike which revs cleanly from tick over through to the redline and will pull from any rev's in any gear, so all in all I'd say that's a pretty good showing.

It will be interesting to see what the KR1S carbs do to the bike, my mate who does all the dyno work reckons they might kill the very low end rev's a little but imporve mid and higher rev's quiet a lot - watch this space for more updates

One last thing with the Banshee coils that we noticed was that the bike starts much easier and throttle response is a lot crisper and looking at the power curve etc on the dyno, they have definately made a difference, so a well worth while upgrade for the cost - will post up a new posting about the coils as well now,.

[marsbar350]

good result dave
sems like a dyno test on a LC helps with releasing some ponies ;D