Topics

1

Technical / Dyno tuning 2 strokes?

« on: August 03, 2011, 01:05:37 AM »

I may be lucky enough to be able to get myself a chassis dyno, as it can be completely written off as a business expense and I have access to one cheaply.

Firstly, I am assuming a dyno designed for cars should be universal enough for bikes? ( I do realise there is such thing as a bike only dyno but that would be quite restrictive), however my main concern is about the oil burnt by 2 strokes.
I remember years ago having a rotary on a dyno, the owner complained a lot about it gummng up his o2 sensor, with a 2 stroke being a lot more oilythis issue could be a lot worse.

If anyone has had experiences running 2 strokes on dyno's and the use of o2 sensors with them Id appreciate any input

2

Technical / Bleeding a hydraulic clutch?

« on: July 23, 2011, 02:15:31 AM »

Just threw in a new top end on my Tm 125 the other day, never having done it on this bike the job still only took half a day all up.
Really is a joy to work on, radiators were left on and thanks to the intake ports going into the bottom end, the carby and reed valve was left in tact, all of which makes the job a lot easier.

The clutch has always felt a bit spongy so while there I thought Id change all the fluid.
First thing I noticed was the fluid was like mud so I took off the hydraulic line, got all fluid out of the master cylinder and slave (where the bleed nipple attachs) and blew out all the gunk with compressed air.

All went well until i tried to get lever pressure. Topping up the master cylinder it seems like no fluid is being  pumped through. Now, my first thought is that the master cylinder is stuffed but further reading suggests filling from the bottom while using a syringe to pump fluid in is necessary.

I will try this method but I'm not convinced, if anyone has any tips on doing hydraulic clutches it would be appreciated. 

3

General Two Stroke Talk / 2 Stroke 300cc as a novice bike?

« on: July 06, 2011, 04:40:07 AM »

I have quite a few bikes, many of which are VMX, with almost everything being a bit impractical for the average punter.
From 125cc Mx'ers to full blown 500cc machines, I prefer bikes a bit wild and a bit different to the norm.

IMO, there is nothing worse than going riding and seeing multiple people on exactly the same machine. To many of us, I am sure that is why the 2 bangers have an extra appeal. Sure, we would like them to be better appreciated and represented, but being the only one riding one in a group is still kinda cool.

Anyway, as I often go riding with friends, family and even females who don't have bikes, I have brought it upon myself to get one "hack" which basically anyone can ride - if nothing else it always means I have someone to ride with.

For the last few years this has been an Xr250.
IMO, this is the essence of a good 4 stroke. Extremely reliable, very easy to ride and requires little maintenance. While out riding on the weekend I realised that the XR does have a few issues. The first, an electric start would be nice - as there is nothing worse than seeing a beginner on the side of a hill struggling with a kick starter, the suspension does have some serious limitations and it is of course, very slow.

Nowadays, trying to find a replacement for this is almost impossible. Given the modern advantages that you should expect when upgrading, ideally I would like something that requires similar maintenance (or only a touch more) while being faster and more capable, however reliability is the main factor.
My first thought was a newer 4 stroke 250cc but with all being so "race inspired" these days I get the feeling while all would be faster, lighter etc, none would be near as trouble free.
Perhaps the Wr250f would be close but when considering this I thought, what about two strokes?

Lately, I have been hearing people rave about the newer 300's, heaps of bottom end power, easy to start, low maintenance and a spread of power which doesn't necessarily scare the shit out of you (assuming you take it reasonably easy).

Can anyone here compare a modern 250cc 4 stroke with a 300cc 2 stroke in terms of it's ability to lug, "feel" of the bike in terms of weight ( rather than actual weight) and general ease of use for a novice?
I know we usually associate these things we expert riders but from what I read, if given respect with the right hand, one could be ideal in this situation.

4

General Two Stroke Talk / 125cc gp vs 125cc mx?

« on: June 25, 2011, 03:08:14 AM »

Given both road racing gp and mx 125's run the same engine, does anyone have any info in terms of what hp each makes, as well as the rpm of the redline ?
I imagine the gp bike would be tuned as the ultimate top end screamer but would like to know the difference between the two.

5

Vintage Two Strokes / History of Maico's

« on: March 20, 2011, 04:13:09 AM »

I have done quite a bit of research over the last few months to find as much info as I can on the progression of Maico's over the last 40 years, primarily between 1969 - 1985 when the brand was still strong.

Though there are masses of sites with info, so much of it seems cut and pasted from the same source and there is very little info which focusses on the changes from one model to the next which is frustrating for an enthusiast who wants to understand the details.

Given we have some experts on here, does anyone care to put something like this together?
I could make a start but the gaps will be like Swiss cheese.

Things like when the square bore was introduced (67 or 69?)
In 1974 the engine had some obvious external changes and then again the magnum was introduced in what I think was 78 which ran to until it got water cooling I believe.
Obviously 81 was the first year of the 490, I can't quite get my head around what happened between that point and 1970 when the 501 was available but 440 seemed like the largest sign apart from a few rare 501's.


Chassis wise, 1974 then 1976 saw major travel changes which looks as if it didn't see any major refinements until 82 when the mono shock was introduced. No doubt quite a bit happened between those points though, particularly the front ends where travel changed and fork legs got thicker.

Visual changes are mostly obvious, but as some model pictures are hard to come by, even this isn't as simple as it sounds.

I realise something like this could take a long time to put together but if anyone has the time and knowledge to do it, it would definitely be appreciated.

6

Technical / TM Levers and other interchangeability

« on: January 19, 2011, 01:49:25 AM »

Hi Guys,

I have a 2001 TM125 and was unlucky to bust a front brake lever the other day. I've been told that the are the same as Honda CR levels however the guy at the local Honda dealer couldn't find a match.

Anyone got any ideas?

7

General Two Stroke Talk / It's 2011 where is the Maico....

« on: January 07, 2011, 02:24:58 AM »

I really don't mean for this post to sound sarcastic as I am a huge Maico fan. We were told to wait and wait, and that they would buck the trend by actually releasing a 2011 in 2011.
Ok, it's 2011, sure it's early days but does anyone have any info as to when the bikes will actually be released?

The Maico site which was updated quite frequently with news reports hasn't seen any updates for almost a month now.
Is the release just around the corner?

8

Technical / Hot Rodding a 500cc 2 Stroke

« on: December 09, 2010, 02:51:25 AM »

I've a 500cc 2 stroke (a 96 model Maico) which for all intents and purposes compares to a CR500.
Though this years Maico is supposed to have a powervale, my barrel is off an earlier bike making it powervalve free.

The bike will only be ridden occaisonly so a practical, smooth machine is not what I am after, rather maximum top end power, ripsnorting 4 stroke killer.

The mods I am doing so far are, replacing the 38mm Bing (which is sadly smaller than my TM125's carby!) with a 44mm Mikuni. The reed valve will be changed for a V Force 3, the cylinder ported as well as the compression raised.
The bike will likely end up with an aftermarket pipe and if possible I'll change the ignition (as the spark does look kinds weak). That's about all that's been decided at the moment.

If anyone has any advice on mods or if there is anyone here who has owned a modified Cr500 I'd be interested to hear your thoughts.

Without sounding like a nob, cost of mods isn't an issue. I suppose I would draw the line if running on race gas becomes a necessity and the engine requires rebuilds ridiculously often.

9

General Two Stroke Talk / Best 2 Stroke Chassis Available?

« on: December 03, 2010, 05:23:25 PM »

Nice to be on this board with fellow 2 stroke enthusiasts.

I have been considering for some time making my own CR500AF killer, it's a shame people bother with the CRF's at all given Honda gave up on 2 strokes so long ago. There is clearly more deserving chassis out there!

The plan would be to utilise one of the newest Zabel 750cc 2 stroke singles (these are like a better developed version of the Maico 685) which are commonly used in side car cross bikes, but I figured it would be best to seek info as to what chassis are the best around.

I know handling can be defined in many ways, obviously with a HP monster such as this something with a bit more rake would be ideal, so high speed stability with modern ergos would be the key.

Keeping the whole thing European would be nice is possible so TM and Gas Gas are high up on the list. If anyone has any input as to how these handle and feel compared to the new Japanese bikes it would be appreciated.