GT big block experiance : New GT crank info added

[eden]

or flat slide delly or an airstriker.. I have an airstriker so one day it might go back on the scooter jetted up right. Ive only ran it on that engine once which was to Whitby I think and it was way way too weak but I couldn't be arsed to change settings on the day so just rode it carful and took it off when I got back.
too many rallys to do to have time to f@@k about.

[Mr G in NYC]

I've got a Lectron carb which I'm thinking of trying on a monster RB 250 which I've just
aquired http://www.lectronfuelsystems.com

Supposed to be the dogs whats its for sprinting . G.

[eden]

Day trip from Birmingham to Sunderland on the GT250


Just 15 mins from the day! One day ill have time to do another edit including clips from the full trip.

I was a bit worried about jetting as I have now changed the worn parts in the carb for new ones. The engine did better than my nerves tbh lol

[cezeta]

is there a gt200 demonstrator in the country? we have a few interested people but they and i want to try it?

[eden]

there are plenty out there now, surely someone near you has one?

[shamrockexpress]

Hi Eden
What temperature is that motor running at???
I notice you keep rolling on and off the throttle a lot is this a good thing considering less fuel is less cooling and if you were a bit lean the last thing you want is cutting down the fuel and cool air going in!!!!
I stand to be corrected since I,m only a young fella

PS since I have got my new fandango temp guage I have seen this quick rise in temperature the minute I roll off the throttle and come upto the road end temperature immediately rises 20-30 % I run a slightly rich pilot jet/ slide set up which quickly settles down so plenty rich there, then once you get going temperature then quickly resumes its self.

[eden]

Rolling off the thottle keeps the CHT temps steady and also enables me to roll to fully open to cool EGT.
With that motor once it's traveling at over 65 it wants to keep climbing RPM and speed if I keep the throtted open. At the same time I don't trust that my needle settings are bang on enough to keep the throttle held at a constant position anywhere between closed and fully open.
If I do keep the throttle held at any position between 1/4 and 3/4 the CHT hold constant but the EGT rises to just over 600 which I don't like. I like to keep the EGT around 580 and the CHT reading under 170.
Also when rolling off the throttle it gives a good indication if the motor is getting too hot as it will ping as you roll off, if it doesn't ping I know all is well, if it does I can either apply some choke for a few seconds or ease off for a few miles.

Another important reason I roll off is to give the motor a chance to nip up if it is too hot. A nip up while off the throtted is much more likely not because less fuel is going through but because the engine isn't forcing the piston up and down as hard as it is when wide open and if it does nip while off the throttle It does a lot less damage to the bore and piston than a size while pushing hard with the throttle wide open.


People for years have said that they siezed after giving it full beans and then letting off the throttle and wrongly presumed it siezed because of a lack of fuel when let off. This can be the case if the tick over is set too low which would mean the engine is being starved of fuel as no air is traveling across the atomiser to pull fuel through, but if set up right it will pull fuel at high rpm with the throttle closed, yes it runs leaner, this can be seen on a dyno when you throttle off, but it does the same if you only roll off a little. For an engine to sieze due to shutting the throttle you would have to have the throttle closed for more than a second before the sieze and it would have to have been running to lean while it was wide open.

You will see in many of my videos that I don't only just roll off, if I've been giving it some at high speed/load I also shut off and pull the clutch for the same reason. Its just to see if it's got hot and wants to sieze or not.

You can't really do the same thing unless your also running cast iron because if you do and find it was getting hot and seizes on nikasil you f@@k the lining.

[shamrockexpress]

Certainly does explain your riding style, which obviously works with the miles you have under your belt !!!!!!sounds like a tried and well tested system and can make all the difference getting to and from your destination without a breakdown.
I also think its a good idea to have the right slide cut away and as large a pilot jet as possible as you have explained this is critical and can help coming of a lean part of the throttle range.
Needle settings really are a minefield for the average joe to set up so all I do is hope I,m in the ball park by bringing in a bit of choke on fast downhill runs just for a piece of mind.
My current experiment stage 4 200 iron is good for long runs and feedback,,,, at least if experiments go wrong there is know big loss........my 250 harry barlow is also iron lined as is the GT186 so like yourself not to keen on nicasil unless its a T5

PS what wheel rims and tyres do run on all these trips?

[eden]

Standard split rims and conti twist sport rear, conti twist race front.

I need tyres but having a problem getting twist sports atm

I did try the race on the back for this year's coast to coast but wore two out just that weekend so concluded they are too soft for me. They are good on the front though.

[shamrockexpress]

I take it air stop tubes?
cheers for now.....................keep munching them miles, I will have to get the 250 HB motor back in for the 4 nations give that GT of yours a good thrashing

BTW who was that riding in front in the sunderland video what was he running?