1043 HPN/Mahle - English Questions

[Ras Thurlo]

I hope you guys dont mind me posting in English:

I am interested in a 1043cc conversion for my ST engine, but there is very little about this modification in the English speaking forums - and I assume that most 1043 engines are in Germany.

I am looking for a torque tractor rather than a race engine. I wanted to try to get a strong and flat torque curve. I spend a lot of my time on technical tracks in low revs 2-3rd gears, so low rev torque is very important to me.

A few questions:

- will the 1043 give me what I am looking for? I assume that the extra cc should give me this

- I have read that most 1043 bikes have the 320 cam, does it also work well with the 308 cam? Instinctively I would prefer to keep the 308 given what I am looking for. But was told that a good compromise on this point is to place the 320 on a slight advance timing to fill out the low revs.

- I have been told that it is best to get r80 heads and modify them, but also have seen that many use OEM r100 heads. Any comments?

- What compression ratio range works best? I wanted a trade-off between performance and ability to work on African fuel.

- are spare parts easily available through HPN, or are they mostly sold as kits with little/no after-sales of specific items?


any feedback gratefully received......

[Birzelbub]

Hello,
my english ist very bad, but I drive a torque tractor with 1043 ccm, heavy pistons and 320° camshaft and comp. 9,5:1 . I have learn the last years from this forum.
A motor with 1043ccm know ist too expensive vs. 1070ccm big bore.

I like my motor. The motor was bild in 2002 and had a long standtime.
I bye the G/S 2010 and drive now 80% offroad. I like to play with my bike trial exercises and the motor is going on very slowly.

I had no chance to drive a big bore, but i will next year.

I think a 308° camshaft is ok, possible better offroad.

[Wilhelm]

Hi Ras,

some additional hints:

for the engine, try Kallenbach, who was/is the main developer. He cooperates with HPN.

Over here, 1043 owners are pretty few (1070 Big Bore is preferred, since it's a lot cheaper).

You will find - if you haven't found yet - quite a few 1043 owners at hpn-forum. Communication in english is no big deal.

[Ras Thurlo]

I drive a torque tractor with 1043 ccm... I like to play with my bike trial exercises and the motor is going on very slowly.

happy to hear it is a torque tractor

Also like riding these bikes for slow technical offroad, its much more work than an EXC, but I find more rewarding

Over here, 1043 owners are pretty few (1070 Big Bore is preferred, since it's a lot cheaper).

I had never previously considered this route because of cost - but found a second-hand unused set at a sensible price. It will cost less than the big-bore and have more retro appeal.

[tom1803]

Hi "Ras Thurlo" - funny Name ...
Retro appeal is good, if the price is good- of course, don´t think about longer, but I only can agree with the other members. My experience with 1070 BBK is very good - 15000 km of which 1000 on the race track (not offroad). No problems.
€ 2,000 well spent.


http://www.siebenrock.com/de/produkt...k/1101100.html

ciao and best regards to Tuscany

Thomas