Starting a 490

[HVA61]

If you use the decompressor , they as easy to start as 125.

The only 490's that Iv'e seen start like a 125 are in need of a re-bore.

Sounds like you need starting lessons for 490's , fresh or tired they are easy to start with a decomp.

The late model decomp valve is actually 18mm not 16mm and they do help a bit. I have seen one 490 with a 2.5mm piston in it and a PVL ignition that will not kick start because it isn't possible to kick it fast enough to make a spark even with the 18mm valve. Push starts no problem if you have a hill.

[Mad Max]

OK, my decompressor is not working so that will be a good start, (I have parts on order).

Are there timing marks on the rotor to check the advance with a timing light?

What does 2.2mm relate to in degrees?

Do these Motoplat ignitions advance the timing automatically (electronically?)

I dont need Maccas Sleepy, I'm a fat bastard!

Thanks all

[sleepy]

OK, my decompressor is not working so that will be a good start, (I have parts on order).

Are there timing marks on the rotor to check the advance with a timing light?

What does 2.2mm relate to in degrees?

Do these Motoplat ignitions advance the timing automatically (electronically?)

I dont need Maccas Sleepy, I'm a fat bastard!

Thanks all

What ignition is fitted to the bike?  Original motosplat or the Bosch enduro or something else?

If you don't need Maccers then of to the GYM with you and start doing those leg things that the gym junkies do.

[Rossvickicampbell]

sounds like a buy a 250 time 

[JohnnyO]

Set the timing with a dial gauge at 2.2mm btdc using the marks on the ignition.
Fit the decomp before you try starting it, you're wasting your time otherwise..

[Mad Max]

Motoplat ignition fitted Sleepy. I dont think I'll be attending the gym, maybe the emergency dept if I do the the bastard going as I havent ridden a dirt bike for years.

A 250 would be smart Rossvickicampbell, but then I've never been accused of being smart!

I'm now out the bush at work until Tuesday so there will be no progess until then.

I will be replacing fork seals next week, any tricks I need to know (I've done them in road bikes many times). What weight oil and how much?

Thanks all.

[sleepy]

With the motoplat there are marks on the stator and rotor which the book specifies to line up at 2.1 +- .1mm btdc. The marks are only good if the rotor and stator are a matched pair, they have a serial number on both parts that should match. You can use a timing light but only to check if the marks still line up at around 3 or 4000 rpm.
The light can't be used to set the timing because as you move the stator the timing marks will always line up.
I have seen a mismatched set were the timing was advanced by about 10 degrees when the marks where staticly set. Nearly broke the owners ankle each time he tried to start it. I have checked the mark alignment by turning the motor over with a drill with the plug out and aiming the timing light at the marks which even at drill speed should be close to linning up(make sure the plug is still earthed and there is no petrol around). You will still have to use a dial indicator down the plug hole to set the 2.1mm.
 
The motoplats do have a bit of electronic advance built in to answer your earlier question.

Fork oil is listed as 20wt at 570cc per leg and 14 psi air pressure. This is a starting piont and the pressure and quantity can be varied to suit rider weight and track conditions.

[davidmc]

2.0mm is close to 22.5 degrees

[FritzG]

Here in the PNW myself and all my big bore Maico bros are running Maxima Castor at 32-1.

It has been my experience that as the Motoplat dies the 490's become increasingly difficult to start. The failure mode on 2 motoplat equipped 490's was that I could not get a fire lit by kicking (I have had lots of 490's that I have raced for years and know how to start them) then even pushing down a hill or towing the bike will not get it started. Time for s new PVL or HPI.

You're onto the decompressor, good!

If you are running the Bing make sure the slide is not worn, if the slide greets you with a big smily face get a new one.

Like the gentleman on the previous post, they like a wet bottom end, I run long vent hoses and will turn them up, tickle until you see a level build in the hoses and hold the throttle open for a count of 3, this floods the bottom end. A few slow priming kicks then get it just past TDC and give it a smooth strong stroke, do not "slap" at the kickstart. If it pops or kicks back shut the fuel off and hold the throttle wide open when kicking.

[KTM47]

I run Shell Advance Racing M in my Maico @ 32/1.  It is a synthetic castor oil like the Maxima 927.

I had trouble starting my 490 it slowly got worse.  I thought it was ignition.  I got a new ignition from HPI in Belgium.  It was $271.00 including postage to Australia.  It kick started after 5 kicks when I fitted it and even started first kick one time.  However after three rides it wouldn't start at all.  After trying several different things I decided there was something else wrong.

Took the motor out and split the cases etc.  Big end worn, but I think the biggest problem was probably a leaking ignition side crank seal.  The bike was also running hotter just before it wouldn't start.

Anyway the problem may not just be one thing.

[Mad Max]

Thanks all. My problem may well be more than one thing.

How did you but the HPI ignition KTM47? Ebay?

Can I change the crankshaft seals without spliting the cases?

[tony27]

You can order off HPI's site
http://www.hpi.be/item.php?item=STK113