to create more crankcase comp

[georgieboy]

Hi all,
I am working on this huskie CR125 from 1999.
At the moment the whole engine is apart to fix up the bigend.
I was hoping to create some more lowend by putting inserts in the crank. The crank comes with 4 holes for counterbalancing the piston and i was thinking to close these to create more crankcase compression.
Am i on the right track or ........
I believe to have read this info here on the forum.
Will it be noticable do it? Or is it neglectable?

 

[georgieboy]

sorry everybody i was too quick with asking. I found a lot of info with the search key.
bi

 

[marcusgunby]

The std husky pipe is a terrible design-alot of HP cna be found with a decent pipe.

 

[georgieboy]

Marcus, huskies are not so common around the world and you happen to know somethings about them. You have't owned one as far as i know, do you?Do you have any recommendations. A lot of guys here in Holland uses HGS pipes, as they are dutch make. Oo keep in mind i need lowend, as i want to use it for woods riding.
Today i took my dremel and cleared the intake path. Made all the transitions round etc. Already blueprinted the cilinder to the cases. Yes i know it is just bogus but i like the idea being bussy with this engine.

 

[marcusgunby]

LOL i have my opionion but i am biased , the dyno work i have done on the RM was done at Karl Prestwoods place, he developed the works husky for copper,nunn and sword etc, the factory huskies only used 2C pipes, these are sold worldwide but not always under the 2C logo, in fact only in the UK and Australia and one other place(forgot where) does the 2C brand exist, in many others the pipes are renamed.I will look into where you buy them from in the netherlands if you want me to.

The hgs was a decent pipe on the rm but not as good as 2c, for real low end you have to totally retune the engine and then it will peak at 9500rpm, it will fall flat on top end.

 

[steve125]

Originally posted by marcusgunby
for real low end you have to totally retune the engine and then it will peak at 9500rpm, it will fall flat on top end.

Or get a 250 four stroke and have it the easy way like most riders that are giving up on the 125. :|  

 

[georgieboy]

Yeah Steven you are right. But that is for the future. First I want to ride this 125. I already own a 250 Huskie. So i ve got my low end, but want something lighter to play with.
I will forget the lowend for now, and focus on a pipe, so pls Yes Marcus, try to find out the name/place in lowlands for me.

 

[DEANSFASTWAY]

Georgie we used to work on alot of these 125s back in the day. They actually were a pretty good motor to run for like a year or so but then when things like the crank went or the clutch basket galled up they werent so hot. We sold quite a few HGS pipes and Pro Circuit . For woodsies with a CR(low end power) we were running the thinnest base gaskets possible and advancing the ign timing and they seemed pretty sturdy down low youll need to run good gas though.Boyesen dual stage reeds seemed good also. I think I also used to plug up the crank holes with cork to help build crank pressure. You could play a bit with the power valve too . We made some big bores also and they made good power. I worked at a dealer very close to the importer around that time .They were pretty good bikes but everything has its maladies. Worst thing though was when the cranks locked up (alot of them) On the 250/360 the cranks lasted forever, go figure.On the 125s I used to kinda grind a swail in the crank halves to sort of funnel oil to the lower bearing, and run like .015" big end play on the rod. Good Luck

 

[cujet]

A general rule to keep 2 stroke connecting rod big end bearings alive longer is to run MORE side clearance. The Husky 125's were fairly tight. Going to the big end of the specs helps some. Aftermarket rods also work well. Leaded fuel is worth using.

Chris

 

[marcusgunby]

Sorry georgieboy i can find any dealers in your local, you could buy from a UK dealer but i dont know if the exchange rate will do you a favour or work against you

heres some dealers
www.1stmx.co.uk

http://www.dirtbikedepot.com/

 

[georgieboy]

First Marcus, thx for looking. Dean is mentioning the HGS pipe so maybe i go that way.
Dean i made a portmap of the cilinder, more for fun than anything else.
On paper it is looking to be nice porting for lowend. I will order a 0.3mm and 0.5mm gasket for the cilinder. And yes i will play with the timing a bit. Here in holland we ve got fairly nice pumpgas 98 octane, so that is covered.
I am doing a bit of grinding in the intake traject. The cases were really obstructing the flow. And i also flowed the reedcases to get a smooth traject there. So all low budget things. I was thinking of stuffing the cranks with cork also. I am bussy drinking wine this weekend to get me some cork. (grin) I am looking forward riding this bike.
Thnks for all the suggestions. bibi George

 

[marcusgunby]

geogiaboy you did see the dyno charts i have up of the HGS vs 2c?

 

http://dirtrider.net/forums3/attachment.php?s=&postid=705495

 

std is green, hgs is blue, 2C is red,The HGS offered a small gian over std but at a price of a huge dip in the mid.

 

[georgieboy]

lol, oke that pipe is out.
I still have the stock pipe though.
Is a dip like that noticable with riding(bear in mind i never rode a 125)?

 

[steve125]

Georgieboy, just because the HGS pipe did not work for Marcus doesn't mean that company's pipe will not work for you.

Just like in any product competition, there are good pipes and also bad one's. The hard part is weeding out the bad one. It's not as simple as saying FMF is good and ProCircuit is bad. Because both company's share in their hits and misses. ;)

 

[DEANSFASTWAY]

Georgieboy . if youre looking for good low end I wouldnt go crazy hogging anything out or overpolishing anything .Most arts and craft stores have bags of different size cork for cheap but youre way sounds like alot of fun! You might want to try to add a venturi seperator in the carby sort of like the power now device. I get sheets of thin carbon fiber the kind used for like electrical circuit boards and cut to fit in carb, Then epoxy in place . I do this on Microsprints where we want a big carb but still need good pull out of the corners. 125 micros have no clutch so you cant fan or slip when the motor lugs . Did you ever think about a dual range Ignition that might be a good thing if you can find one cheap somewhere.The FMFs were big bucks when they first came out and then We saw then cheap on closeouts (in the states anyway)for like 100 dollars or so. they didnt really catch on that well . Either did the Aluminum Powerbrand pipes.

 

[georgieboy]

Steve, i was merely kidding about the pipe. I know that each engine reacts differently to pipe combo's. (that is what i learned here) But i don't have the opportunity to test different combo's so i probably stick to the original(after cleaning the inside a bit)
And Dean, yes it is fun this way.
And about the grinding. I try not to be too enthuastic with it, but it is just fun doing something I see as tuning. I started with just the casting flaws at the cases edges, but after I saw a nice grinded Honda case I started cutting the edge of the cases to get a nice angle into the cilinderports.
Am i doing the right thing here.
BTW i also made a portmap and looking at it, i dare to say the blowdown with opened valve is rather conservative. approx 26 degrees. Are you agreeing with me? With closed valve it comes to 10 degrees. It is this why they said the engine lacks power at top revs?