The OTHER crossing from Mexico to Guatemala
 

I crossed the river from Mexico to Guatemal at Frontera Corozal. It was a lot of fun. When you enter the down you will have to pay 15 pesos to enter because of the ruins, the follow the paved road all the pay to the river. The immigration office is on the right hand side, I think it is a terquoise color and it is gated, ask anyone and they will know. After you stop there dont bother with the people stopping you as you make your way to the river, they charge a lot more then the people at the river, plus you can bargin with them easier once at the river. I pain 200 pesos for me and the bike because I took the first offer when stopped on the road. I worked my way from 800 to 400 to 200 pesos. You can get a better deal at the river. Anyway you will put your bike in the boat cross and it is a little difficult to get it up the other side fully loaded but there will be people there to help and a LASO tied to the front of the bike with someone pulling is a great idea. Once you are up the bank head south to Bethel about a 20 minute ride. The town on the other side is no place I wanted to hang out. Once you come to the intersection at the end of the road stay STRAIGHT/ LEFT dont go RIGHT. The immiration office is on the left, the only building there, you cant miss it. If you see a lot of houses, stores and people turn around you went into Bethel and the immigration office is the other way. You can exchange pesos and dollars at the hut next to the immigration office too. If the lady that owns it isnt there then ask if you can meet her on your way to Flores, we did and it worked great. The officer in the immigration office speaks English very well and it was only $5. The whole crossing was exciting and easy. The road to Flores was rough dirt but fun. I had to cross some flooded parts about halfway to my knees but it was fun.
If you need anymore information let me know I highly recommed this crossing.

Yep,its cool, did it going the other way and paid $20 for the boat.

I think the only thing to watch is if you're coming from Mexico, you may have had to use your credit card for the temp import when you arrived in Mexico but if you don't sign out within 30 days, you might get charged something like $300 as there is no Aduana at this border, the nearest one being in Palenque. If you paid cash at the border, you'd probably be fine.

Coming the other direction, I ended up not having any temp import paperwork for my bike as the Immigration guys in Palenque couldn't be bothered to do the paperwork so when entering the USA, I breezed straight through while my partner who came in to Mexico from Belize had to go back to Mexico to try and clear their temp import.

Yes I crossed there too last year From USA to Venezuela , solo motorcycle trip . It was fun indeed. I regretted it later though when I was back in Venezuela and I hadn't cancelled my Mexican vehicle import permit.

Corozal crossing
 

I did this in Jan. It was raining when we arrived. No one asked for money. We stopped and ate and got local info at the restaurant on the north side of street.

Getting up the river bank in the mud was difficult. The amazing part was watching them take an F150 pickup accross on a pair of boats.

We didn't process any paperwork when we left Mexico. Entered Guatemala at Bethel and a couple days later reentered Mexico at La Masilla. We acted like we were clueless (mostly true) and I think the whole experience was around $35.

Thanks for the information guys. I am in Frontera Corozal right now and had a chat witht he mexican migracion officer. it seems straightforward. he said the road from bethel to Flores is unpaved for 50km, after which it is straightforward. Aduana is indeed in Flores only, not in bethel. i can get the bike checked in at Flores apparently. However, it is the $50 for the bike crossing across the river and the thoguht of the unpaved road for 50km that worries me. I might just be a good boy and do the La Messila crossing.
But am sorely tempted.

Can anyone tell me how bad the unpaved road section is? my bike is rather heavy with all the gear.
Also, any advise with getting the moto on to the launch? How much did you help the bystanders get the bike on and off the llancha?