Tunnel Set Up, Props & Engine Tuning

[The Real Grim]

Tim,

Question 1 - I haven't disconnected the water cooling yet

Question 2 - The 1440 b/c was on it when I lengthened the pipe

I'm really looking forward to next Sunday at Penrith where hopefully, we'll get some reasonable water for more accurate testing. I'll have to get there early!

Thanks,

James

James, This is what i would do #1 leave the water on yes the 21motar likes to run hot but by taking the water all the way off you will end up blowing the sleeve out of round because of it getting to hot. I would leave the water on but squeeze it down about half .#2 please remember this load=x pipe =y motar=z

in short x,y,z when you have these thing right hold on because your gonna go fast. Now the C.M.B 21 r/s

that you are running has a lot of power it can pull a big prop but if you don't run a big enoff prop you will tend to lean it down to far and take plugs out.So i would check the deck clerance on the motar and make it no less then 8 thousands because the head volume is to big. The head also has a conicle cut on it which get's read of heat to so by doing this you will biuld heat in the motar but not getting it to hot. Then you have to richen up the needle witch will make more power so thats the Z part.Then there is the load factor which is X .Now Mark Sholund is right the 1440 prop is faster but hard to set up when you get everything right the 4053 prop

is faster in the corner and makes the boat not so touchey i would put the 4053 on it and run it. Find rich on the needle but dont lean it down to far to make it go in the straits.This is where Y comes to play start shoveing the pipe in untill it dose not want to come on the pipe very easy and then pull it out a 1/4 inch now you have your load and your pipe and your motar working at the best it can. and going to 40 persent nitro was a good thing the more nitro and alcohol you can run the ritcher the motar will get. Its just more fule to burn and we all no that the more fuel you and burn the more power you will make and the faster you will go. So i hope this helps and good boating.

sincerly ,

Chris Grim

p.s if the spelling is not right it was late and i couldn't find spell check :unsure:

 

[Tim_Duggan]

I think James was happy with the results we got yesterday........ B) It's more than fast enough for him at the moment - and there is room for improvement.

Mark S - I think the 40x53 and 1440 James has from you will need de-cupping. Too much cup to stop it staging properly on pipe. For your reference - it pulls a stock X637 nicely with the engine cold to great rpm's. It came on easily and held it on in the turns with that prop also.

Tim.

 

[kesso2118]

Tim is the master of the understatement, I'm "over the moon" with the performance he got for me yesterday. He worked his magic on the CMB and really brought it to life.

We put on Tim's X438 to start the session and I thought we would throw the boat in and see how it went - NOPE!

Tim got me to start up the engine, listened to it for about 3 seconds and got me to shut it down. We then adjusted the throttle cable to make sure I was getting maximum throttle opening and he then twiddled with the low and high end needles.

We then put the boat in for its first run and YAHOO!!!!! The CMB was making BIG noise and giving the TS2 a very serious push in the backside.

We then spent the next couple of hours adjusting the set up and my driving technique (or lack of technique) to get the boat to stay on the water. It was really flying down the straights and pretty wild coming out of the turns.

We gradually lowered the engine height and added some extra weight at the CG. We adjusted the trim angle to take out any positive and it became a bit easier to keep on the water.

We then tried an X637 and it maintained its high revs and speed down the straight and was a bit safer in the turns.

We then tried the 144b/c with no changes to set up and while it was faster than my outings in the previous few weeks it wasn't pulling the same revs or speed that we were getting with the X637.

I put the X637 back on a spent the rest of the day trying to improve my driving.

The focus for the next session will be to settle the boat down through the turns. We will start by removing the 4ozs of lead from the nose of the cowl and rebalancing the boat with weight on the CG.

Thanks to Tim for his help and everyone who has contributed the advice in this Forum.

Regards,

James

 

[Jerry Wyss]

I was waitin' to hear that one, I must say, I'm not surprised with Tim involved.

I imagine the diff in cup might be that these guys (well, Mark) is running 70%

nitro, think I remember hearing that.

Better ditch that TT Tim or these guys your helping will be climbing up your six :lol:

Jerry, hahaha

 

[Tim_Duggan]

Thanks to Tim for his help and everyone who has contributed the advice in this Forum.

Regards,

James

No problem - glad to help.

JW - most of the guys in the club are faster than me - to be honest it doesn't bother me (yet) because we are all having fun in the class. Somehow I don't think it would be as much fun if I was running a more expensive engine / hull combination.

Tim

 

[Jerry Wyss]

Fun is the most important factor to me too,,, and being a TT mate it gives you the license

to "chill", hahaha . It's also a real treat to see somebodys face when they find out they're

boat really is fast

Ya Done Good!

 

[Craig Murphy]

Yeah thanks again to Tim for the guidance on setting up the MAC yesterday, Tim your advice and help to us newbie's is very much appreciated.

James it's good to see another TS2 going hard.... bit more time on the handling and that boat will be a real screamer...

 

[kesso2118]

I ran the TS2/CMB .21 RS yesterday without any weight in the nose of the cowling and handling in the corners was much improved!! The boat is becoming more predictable and easier to manage.

I took out about 4.5 oz from the nose and we are running with about 4.25 oz on the C/G (i.e. between the radio box and the fuel tank).

The boat starts to get light just before the end of the straight and if I back off slightly to settle it down I am able to initiate the turn at a reasonably high speed and the steering is very precise.

Previously, I was finding that the boat would go into the turn OK at speed but seemed to understeer and I needed to give it more rudder through the turn and/or reduce the speed. This would then result in wild bouncing coming out of the turn.

Now, if I maintain the speed through the turn and use minimal rudder the boat tracks smoothly around the turn.

On another note, as the day progressed I began to experience some unusual variations in engine performance e.g. sometimes peaking out well and other times not being able to get it onto the pipe. When I brought it back in from one run I found the carby had become loose. Another lesson now learned with the CMB, in addition to using Loctite on the Flywheel Nut, replace the stock nut on the Carby retainer with a nylock nut.

Regards,

James

 

[shoboat]

Tim & James,

You guys need a little more NITRO 70% for sure. Try a X-640 cut to 38 mm and 1/4" Barr-cut down low by the hub

on the Trailing Edge. It is One Wicked Fast Propeller. :lol: Note: If you can't get it to pull easy, back down the cup

on the trailing edge and you will be VERY HAPPY!!! It is a 50+ MPH propeller with some good RPM.

Happy Holidays,

Mark Sholund